US20090004566A1 - Negative Electrode for Non-Aqueous Electrolyte Secondary Batteries, and Non-Aqueous Electrolyte Secondary Battery Having the Same - Google Patents
Negative Electrode for Non-Aqueous Electrolyte Secondary Batteries, and Non-Aqueous Electrolyte Secondary Battery Having the Same Download PDFInfo
- Publication number
- US20090004566A1 US20090004566A1 US11/664,805 US66480506A US2009004566A1 US 20090004566 A1 US20090004566 A1 US 20090004566A1 US 66480506 A US66480506 A US 66480506A US 2009004566 A1 US2009004566 A1 US 2009004566A1
- Authority
- US
- United States
- Prior art keywords
- negative electrode
- binder
- silicon
- current collector
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/364—Composites as mixtures
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/621—Binders
- H01M4/622—Binders being polymers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/70—Carriers or collectors characterised by shape or form
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- the present invention relates to a negative electrode for non-aqueous electrolyte secondary batteries, and more particularly to a technology for extending the life of a negative electrode using a composite negative electrode active material containing silicon-containing particles as active material cores.
- non-aqueous electrolyte secondary batteries smaller in size, lighter in weight, and higher in energy density.
- carbon materials such as graphite are used as a negative electrode active material in practical applications.
- carbon materials have a theoretical capacity density of as low as 372 mAh/g.
- the negative electrode active material are used silicon (Si), tin (Sn), germanium (Ge), an oxide thereof, and an alloy thereof which can form alloys with lithium.
- silicon-containing particles such as silicon particles and silicon oxide particles have been widely studied because they are less expensive.
- cycle characteristics charge-discharge cycle characteristics
- Japanese Patent Unexamined Publication No. 2004-349056 discloses a technology using composite particles (composite negative electrode active material) produced as follows: active material particles containing metal or semimetal that can form lithium alloys are used as the cores (active material cores), and a plurality of carbon fibers are bound to each of the active material cores. It has been reported that this structure can ensure the conductivity even if the active material particles change in volume, thereby maintaining sufficient cycle characteristics. Negative electrodes having high capacity and high functionality are considered to be structured, for example, by using a technology for adequately combining binders that are disclosed in Japanese Patent Unexamined Publication No. H11-354126, in addition to the former technology.
- the present invention provides a negative electrode for non-aqueous electrolyte secondary batteries having high cycle characteristics, and a non-aqueous electrolyte secondary battery having the negative electrode.
- the increase in impedance of the whole negative electrode is suppressed by maintaining the binding force among composite negative electrode active materials in a mixture layer, and also by maintaining the binding force between the mixture layer and a current collector.
- the negative electrode for non-aqueous electrolyte secondary batteries of the present invention has a current collector and a mixture layer.
- the mixture layer contains a composite negative electrode active material, a first binder, and a second binder.
- the mixture layer is formed on the current collector.
- the composite negative electrode active material contains a silicon-containing particle capable of charging and discharging at least lithium ions, a carbon nanofiber (hereinafter, CNF), and a catalyst element.
- the CNF is attached to the surfaces of the silicon-containing particle.
- the catalyst element is at least one selected from the group consisting of copper (Cu), iron (Fe), cobalt (Co), nickel (Ni), molybdenum (Mo) and manganese (Mn), and promotes the growth of the CNF.
- the first binder is composed of an acryl-group-containing polymer.
- the second binder is composed of an adhesive rubber particle. The first binder binds the silicon-containing particle to the current collector, and the second binder binds CNFs together.
- the first binder has a high affinity to the silicon-containing particle
- the second binder has a high affinity to the CNF.
- the current collector has a high affinity to the first binder.
- Each composite negative electrode active material containing the CNF is bound together by the second binder, and the composite negative electrode active material is bound to the current collector through intermediately existing chemical bonds provided by the first binder. Binding in the mixture layer and binding of the mixture layer to the current collector become tight. Therefore, even if the silicon-containing particles expand and contract during charge and discharge, the conductive structure in the mixture layer and the conductive structure between the mixture layer and the current collector are kept. As a result, the cycle characteristics are improved.
- the present invention further provides a non-aqueous electrolyte secondary battery employing a negative electrode containing the aforementioned composite negative electrode active material.
- FIG. 1 is a transparent plan view showing a structure of a model cell in accordance with a first exemplary embodiment of the present invention.
- FIG. 2 is a sectional view of the model cell shown in FIG. 1 taken along line A-A.
- FIG. 3 is a schematic sectional view showing a structure of a mixture layer near a current collector of a negative electrode for non-aqueous electrolyte secondary batteries in accordance with the first exemplary embodiment of the present invention.
- FIG. 4 is a sectional view showing another structure of the negative electrode for non-aqueous electrolyte secondary batteries in accordance with the first exemplary embodiment of the present invention.
- FIG. 1 is a transparent plan view showing the structure of a model cell produced to evaluate a negative electrode for non-aqueous electrolyte secondary batteries of the first exemplary embodiment of the present invention.
- FIG. 2 is a cross sectional view taken along line 1 B- 1 B.
- FIG. 3 is a schematic diagram showing a structure of a mixture layer near a current collector.
- Negative electrode 1 shown in FIGS. 1 and 2 has mixture layer 1 B that is disposed on current collector 1 A and electrically connected to current collector 1 A.
- mixture layer 1 B contains an assembly of composite negative electrode active material 14 .
- Each assembly of composite negative electrode active material 14 contains a silicon-containing particle 11 capable of charging and discharging lithium ions, and a number of carbon nanofibers (hereinafter, CNFs) 12 attached to silicon-containing particle 11 .
- CNFs 12 are grown using, as a core, catalyst element 13 which is dispersed and supported on the surface of silicon-containing particle 11 .
- Catalyst element 13 is at least one selected from the group consisting of copper (Cu), iron (Fe), cobalt (Co), nickel (Ni), molybdenum (Mo), and manganese (Mn), and promotes the growth of CNFs 12 .
- Mixture layer 1 B further contains first binder 15 composed of an acryl-group-containing polymer and second binder 16 composed of adhesive rubber particles. First binder 15 binds silicon-containing particle 11 to current collector 1 A, and second binder 16 binds CNFs 12 together.
- Counter electrode 2 made of metallic lithium is faced to negative electrode 1 via separator 3 .
- Current collector 2 A is bonded to counter electrode 2 on the side opposite to separator 3 .
- These components are accommodated in laminate bag 4 .
- Laminate bag 4 is also filled with non-aqueous electrolyte 5 and sealed. In other words, non-aqueous electrolyte 5 is interposed between negative electrode 1 and counter electrode 2 .
- Current collectors 1 A and 2 A are connected with leads 1 C and 2 C extended to the outside of the cell, respectively. Leads 1 C and 2 C are heat-welded together with modified polypropylene film 7 placed at the opening of laminate bag 4 , so that laminate bag 4 is sealed.
- Silicon-containing particle 11 can be made of Si or SiOx (where, 0.05 ⁇ x ⁇ 1.95, preferably 0.3 ⁇ x ⁇ 1.3), or can be made of an alloy, a compound, a solid solution or the like in which Si is partly replaced with at least one element selected from B, Mg, Ni, Ti, Mo, Co, Ca, Cr, Cu, Fe, Mn, Nb, Ta, V, W, Zn, C, N, and Sn.
- Silicon-containing particles 11 may be composed of one kind or a plurality kinds of the above-mentioned materials.
- Examples of silicon-containing particles 11 composed of the plurality kinds include a compound containing silicon, oxygen, and nitrogen, and a composite of a plurality of compounds containing silicon and oxygen in different ratios.
- silicon-containing particles 11 contain at least one selected from the group consisting of pure silicon, a silicon-containing alloy, a silicon-containing compound, and a silicon-containing solid solution.
- the shapes and kinds of silicon-containing particles 11 and magnitudes of the expansion and contraction are not especially limited. Of these, SiOx is desirable because its discharge capacity density is large and its expansion coefficient during charge is smaller than that of pure silicon.
- CNFs 12 attach to the surface of each silicon-containing particle 11 where they start to grow. In other words, CNFs 12 attach directly to the surface of silicon-containing particle 11 without a binder therebetween. In some growing conditions, CNFs 12 may be chemically bonded to the surface of silicon-containing particle 11 at least at one end thereof which is the starting point of the growth. This reduces the resistance to current collection and assures high electronic conductivity in the battery, thereby providing sufficient charge-discharge characteristics. In a case where CNFs 12 attach to silicon-containing particle 11 via catalyst element 13 , CNFs 12 hardly become detached from silicon-containing particle 11 . Therefore, negative electrode 1 becomes more resistant to a rolling load, namely a mechanical load that is applied to the negative electrode when the negative electrode is rolled to increase filling density thereof.
- catalyst element 13 is preferably present in a metallic state in the surface parts of silicon-containing particles 11 .
- Catalyst element 13 is preferably present in the form of metal particles having a diameter of 1 nm to 1000 nm, for example.
- the metal particles of catalyst element 13 are preferably oxidized.
- CNFs 12 have a fiber length of preferably 1 nm to 1 mm, and more preferably 500 nm to 100 ⁇ m. When the fiber length is less than 1 nm, the effect to increase electrode conductivity is too small. In contrast, the fiber lengths of over 1 mm tend to reduce the active material density or capacity of the electrode.
- CNFs 12 are preferably in the form of at least one selected from the group consisting of tube-shaped carbon, accordion-shaped carbon, plate-shaped carbon, and herringbone-shaped carbon. CNFs 12 may absorb catalyst element 13 during their growth.
- CNFs 12 have a fiber diameter of preferably 1 nm to 1000 nm, and more preferably 50 nm to 300 nm.
- Catalyst element 13 in a metallic state works as an active site to grow CNFs 12 . More specifically, CNFs 12 start to grow when silicon-containing particles 11 having catalyst element 13 that is exposed in a metallic state on their surfaces are introduced into a high-temperature atmosphere containing the source gas of CNFs 12 . When silicon-containing particles 11 have no catalyst element 13 on their surfaces, CNFs 12 do not grow.
- Methods for forming metal particles composed of catalyst element 13 on the surfaces of silicon-containing particles 11 are not particularly limited; however, one preferable method is to support metal particles on the surfaces of silicon-containing particles 11 .
- silicon-containing particles 11 When the metal particles are supported in this method, it is possible to mix silicon-containing particles 11 with the metal particles in solid form; however, it is preferable to soak silicon-containing particles 11 in a solution dissolving a metal compound serving as the source material of the metal particles in an appropriate solvent. After silicon-containing particles 11 are soaked in the solution, the solvent is removed from silicon-containing particles 11 , and then they are heated if necessary. In this way, can be obtained silicon-containing particles 11 which support, on their surfaces, metal particles composed of catalyst element 13 having a diameter of 1 nm to 1000 nm, preferably 10 nm to 100 nm, in a highly and uniformly dispersed state.
- the diameter of the metal particles of catalyst element 13 is preferably 1 nm or more and 1000 nm or less.
- the metal compound to provide the aforementioned solution examples include nickel nitrate, cobalt nitrate, iron nitrate, copper nitrate, manganese nitrate, and hexaammonium heptamolybdate tetrahydrate.
- the solvent used for the solution can be appropriately selected from water, an organic solvent, and a mixture of water and an organic solvent, in consideration of the solubility of the metal compound and the compatibility of the compound with the electrochemical active phases contained in silicon-containing particles 11 .
- the electrochemical active phases mean, of crystal phases or amorphous phases composing silicon-containing particles 11 , the crystal phases or amorphous phases metallic phases and metallic oxide phases that allow an oxidation-reduction reaction accompanied by electron transfer, namely a battery reaction.
- the organic solvent include ethanol, isopropyl alcohol, toluene, benzene, hexane, and tetrahydrofuran.
- alloy particles containing catalyst element 13 it is also possible to synthesize alloy particles containing catalyst element 13 and to use them as silicon-containing particles 11 .
- alloys of silicon and catalyst element 13 are synthesized by a common alloying method.
- the silicon element reacts electrochemically with lithium to form alloys, thereby forming the electrochemical active phases.
- the metallic phases of catalyst element 13 are at least partly exposed in the form of particles having a diameter of 10 nm to 100 nm, for example, on the surfaces of the alloy particles.
- the content of the metal particles or metallic phases of catalyst element 13 is preferably 0.01 wt % to 10 wt % of silicon-containing particles 11 , more preferably 1 wt % to 3 wt %.
- the content of the metal particles or the metallic phases is too low, it takes a lot of time to grow CNFs 12 , thereby decreasing production efficiency.
- catalyst element 13 agglomerates and grows CNFs 12 uneven and having large fiber diameters. This leads to decrease in conductivity and active material density of mixture layer 1 B. This also leads to relative decrease in the proportion of the electrochemical active phases, making it difficult to use composite negative electrode active material 14 as a high-capacity electrode material.
- This production method includes the following four steps of (a) to (d).
- Catalyst element 13 is at least one selected from Cu, Fe, Co, Ni, Mo, and Mn, and promotes the growth of CNFs 12 .
- composite negative electrode active material 14 may be subjected to heat treatment in the air at 100° C. or higher and 400° C. or lower to oxidize catalyst element 13 .
- the heat treatment at this temperature range can oxidize only catalyst element 13 without oxidizing CNFs 12 .
- the method of loading catalyst element 13 on the surfaces of silicon-containing particles 11 at Step (a) is not limited especially. However, there may be mentioned, a step of supporting the metal particles of catalyst element 13 on the surfaces of silicon-containing particles 11 , a step of reducing the surfaces of silicon-containing particles 11 containing catalyst element 13 , a step of synthesizing alloy particles of silicon and catalyst element 13 , and other steps.
- CNFs 12 start to grow when silicon-containing particle 11 having catalyst element 13 at least in the surface part thereof is introduced into a high-temperature atmosphere containing the source gases of CNFs 12 .
- silicon-containing particles 11 are put in a ceramic reaction vessel and heated to high temperatures of 100° C. to 1000° C., preferably to 300° C. to 600° C., in an inert gas or a gas having a reducing power. Then, carbon-containing gas and hydrogen gas, which are the source gases of CNFs 12 , are introduced into the reaction vessel.
- CNFs 12 When the temperature in the reaction vessel is lower than 100° C., CNFs 12 either do not grow or grow very slowly, thereby damaging the productivity. In contrast, when the temperature in the reaction vessel exceeds 1000° C., the source gases are decomposed rapidly to make it harder to grow CNFs 12 .
- the source gases are preferably a mixture gas of carbon-containing gas and hydrogen gas.
- the carbon-containing gas include methane, ethane, ethylene, butane, and carbon monoxide.
- the molar ratio (volume ratio) of the carbon-containing gas in the mixture gas is preferably 20% to 80%.
- Step (c) silicon-containing particles 11 having CNFs 12 attached thereto are sintered in an inert gas atmosphere at 400° C. or higher and 1600° C. or lower.
- This sintering is preferable because it can improve crystallinity of CNFs 12 , suppress the irreversible reaction which progresses at the initial charge of the battery between electrolyte 5 and CNFs 12 , and hence achieve excellent charge-discharge efficiency of the battery.
- the irreversible reaction may not be suppressed, decreasing the charge-discharge efficiency of the battery.
- the electrochemical active phases of silicon-containing particles 11 react with CNFs 12 and may be inactivated or reduced, so that the charge-discharge capacity of the battery may be decreased.
- the electrochemical active phases of silicon-containing particles 11 are made of silicon
- the silicon reacts with CNFs 12 to generate inert silicon carbide, thereby decreasing the charge-discharge capacity of the battery.
- the sintering temperature is particularly preferably 1000° C. or higher and 1600° C. or lower.
- Step (c) Improving the crystallinity of CNFs 12 suppresses the irreversible reaction between electrolyte 5 and CNFs 12 , as discussed above.
- Step (c) is not always necessary.
- composite negative electrode active material 14 is preferably heat-treated in the air at 100° C. or higher and 400° C. or lower in order to oxidize at least parts (surfaces, for example) of the metal particles or metallic phases of catalyst element 13 .
- the heat-treatment temperature is lower than 100° C., it is difficult to oxidize the metal.
- the temperature exceeds 400° C., grown CNFs 12 may burn.
- Step (d) sintered silicon-containing particles 11 with CNFs 12 attached thereto are crushed. Crushing is preferred, because composite negative electrode active material 14 of sufficient filling property is obtained. However, when the tap density of the particles is 0.42 g/cm 3 or more and 0.91 g/cm 3 or less without crushing, crushing is not always necessary. In other words, when silicon-containing particles with sufficient filling property are used as a source material, Step (d) is not always necessary.
- Composite negative electrode active material 14 composed of silicon-containing particles 11 having CNFs 12 on their surfaces are mixed with first binder 15 , second binder 16 , and a solvent to prepare a negative electrode mixture slurry.
- First binder 15 is a polymer containing an acryl group as described above.
- an example of first binder 15 includes polyacrylic acid, polyacrylic ester, polymethacrylic acid, and polymethacrylic ester.
- polyacrylic acid and polymethacrylic acid that contain a carboxyl group are preferable because the hydrogen atom contained in the carboxyl group form hydrogen bond with metallic atoms to provide a high binding force.
- Second binder 16 is an adhesive rubber particle.
- An example of second binder 16 includes styrene-butadiene copolymer (SBR). Especially, core-shell-type modified SBR that is designed so that the core has elasticity and the shell has adhesion is more preferable.
- SBR styrene-butadiene copolymer
- solvent examples include N-methyl-2-pyrrolidone (NMP) and water.
- the obtained slurry is applied to both surfaces of current collector 1 A using a doctor blade, and dried, thereby forming mixture layer 1 B on current collector 1 A.
- appropriate adjustment of the drying condition can provide a structure where first binder 15 binds silicon-containing particles 11 to current collector 1 A, and second binder 16 binds CNFs 12 together.
- the temperature and air flow are adjusted during drying.
- Second binder 16 having the property of moving with evaporating solvent accumulate more on the portion of mixture layer 1 B relatively close to the surface thereof as compared with the vicinity of current collector 1 A.
- a structure where first binder 15 binds silicon-containing particles 11 to current collector 1 A is obtained.
- mixture layer 1 B is rolled to adjust its thickness.
- the obtained long strip of negative electrode is either stamped or cut into a predetermined size.
- Lead 8 made of nickel or copper is connected to the exposed part of current collector 1 A, for example by welding or the other methods, to complete negative electrode 1 .
- Current collector 1 A can be a metal foil made of stainless steel, nickel, copper, or titanium, or a thin film made of carbon or a conductive resin. Current collector 1 A may also be surface-treated with carbon, nickel, titanium, or the like.
- nonaqueous electrolyte 5 can include an electrolyte solution dissolving a solute in an organic solvent and a polymer electrolyte where the electrolyte solution is immobilized with a polymer.
- separator 3 is formed of non-woven fabric or micro porous film made of polyethylene, polypropylene, aramid resin, amide-imide, polyphenylene sulfide, or polyimide.
- the inside or surface of separator 3 may contain a heat-resistant filler such as alumina, magnesia, silica, and titania.
- a heat-resistant layer that is made of these fillers and the same binder as that used in the electrode may be disposed.
- nonaqueous electrolyte 5 is selected based on oxidation-reduction potential of active material, and others.
- solute preferably used in nonaqueous electrolyte 5 include the following materials: LiPF 6 ; LiBF 4 ; LiCiO 4 ; LiAlCl 4 ; LiSbF 6 ; LiSCN; LiCF 3 SO 3 ; LiCF 3 CO 2 ; LiAsF 6 ; LiB 10 Cl 10 ; lower aliphatic lithium calboxylate; LiF; LiCl; LiBr; LiI; chloroborane lithium; various borates such as bis(1,2-benzendiolate (2-)-O,O′) lithium borate, bis(2,3-naphthalenediolate (2-)-O,O′) lithium borate, bis(2,2′-biphenyldiolate (2-)-O,O′) lithium borate, and bis(5-fluoro-2-olate-1-benzensulfonic acid-O
- the organic solvent for dissolving the solute is a solvent generally used in a lithium battery such as one or a mixture of the following solvents: ethylene carbonate; propylene carbonate; butylene carbonate; vinylene carbonate; dimethyl carbonate; diethyl carbonate; ethyl methyl carbonate; dipropyl carbonate; methyl formate; methyl acetate; methyl propionate; ethyl propionate; dimethoxymethane; ⁇ -butyrolactone; ⁇ -valerolactone; 1,2-diethoxyethane; 1,2-dimethoxyethane; ethoxymethoxyethane; trimethoxymethane; tetrahydrofuran derivatives such as tetrahydrofuran and 2-methyl-tetrahydrofuran; dimethyl sulfoxide; dioxolane derivatives such as 1,3-dioxolane and 4-methyl-1,3-dioxolane; formamide; acet
- the solvent may further contain an additive such as vinylene carbonate, cyclohexylbenzene, biphenyl, diphenyl ether, vinylethylene carbonate, divinylethylene carbonate, phenylethylene carbonate, diallyl carbonate, fluoroethylene carbonate, catechol carbonate, vinyl acetate, ethylene sulfite, propanesultone, trifluoropropylene carbonate, dibenzofuran, 2,4-difluoroanisole, o-terphenyl, and m-terphenyl.
- an additive such as vinylene carbonate, cyclohexylbenzene, biphenyl, diphenyl ether, vinylethylene carbonate, divinylethylene carbonate, phenylethylene carbonate, diallyl carbonate, fluoroethylene carbonate, catechol carbonate, vinyl acetate, ethylene sulfite, propanesultone, trifluoropropylene carbonate, dibenzofuran, 2,4-difluoro
- Nonaqueous electrolyte 5 may be used in the form of solid polymer electrolyte by mixing or dissolving the solute into one or a mixture of the following polymer materials: polyethylene oxide; polypropylene oxide; polyphosphazene; polyaziridine; polyethylene sulfide; polyvinyl alcohol; polyvinylidene fluoride; polyhexafluoropropylene and the like.
- the solid polymer electrolyte may be used in a gel form by being mixed or dissolved into the above-mentioned organic solvent.
- the solid electrolyte made of an inorganic material such as the following material may be used: lithium nitride; lithium halide; lithium oxoate; Li 4 SiO 4 ; Li 4 SiO 4 —LiI—LiOH; Li 3 PO 4 —Li 4 SiO 4 ; Li 2 SiS 3 ; Li 3 PO 4 —Li 2 S—SiS 2 ; a phosphorus sulfide compound and the like.
- Laminate bag 4 is made of a sheet produced by laminating a hot-melt resin film such as polyethylene on at least one side of a metal foil such as an aluminum foil. The sheet is processed in a bag shape so that the hot-melt resin film forms the inner surface of the bag. The hot-melt resin film on the inner surface is thermally welded to itself, thereby sealing the inside of laminate bag 4 .
- mixture layer 1 B contains composite negative electrode active material 14 , first binder 15 composed of an acryl-group-containing polymer, and second binder 16 composed of adhesive rubber particles.
- First binder 15 binds silicon-containing particles 11 to current collector 1 A, and second binder 16 binds CNFs 12 together.
- first binder 15 composed of an acryl-group-containing polymer
- silicon-containing particles 11 are bound to current collector 1 A, but each assembly of composite negative electrode active material 14 is hardly bound together.
- Composite negative electrode active material 14 can be therefore apt to separate from mixture layer 1 B during charge and discharge.
- second binder 16 composed of adhesive rubber particles
- each assembly of composite negative electrode active material 14 is bound together via CNFs 12 , but is hardly bound to current collector 1 A.
- a large part of mixture layer 1 B is peeled off from current collector 1 A during charge and discharge.
- first binder 15 and second binder 16 are simply mixed and uniformly dispersed (distributed) in mixture layer 1 B, the property of each binder is not sufficiently exhibited and hence a large part of mixture layer 1 B is peeled off from current collector 1 A during charge and discharge. Therefore, it is essential that first binder 15 binds silicon-containing particles 11 to current collector 1 A and that second binder 16 binds CNFs 12 together.
- the surface of current collector 1 A is preferably roughened.
- the area to which first binder 15 having a high affinity to current collector 1 A sticks increases, so that the binding property of current collector 1 A improves, and that the cycle characteristics improve.
- Examples of the roughening method include a sandblast method, plating at a high current density, and chemical etching. It is desirable that the surface obtained by roughening have a roughness of 1 ⁇ m or more and 5 ⁇ m or less.
- first binder 15 having a high affinity to current collector 1 A be made higher near current collector 1 A than in other part in mixture layer 1 B.
- the other part means the positions closer to the surface of mixture layer 1 B.
- several kinds of negative electrode mixture slurry having different contents of first binder 15 are prepared, and the slurry is applied to current collector 1 A in the descending order of the contents of first binder 15 .
- the content of first binder 15 can be made to be higher near current collector 1 A.
- binding layer 20 where the content of first binder 15 is higher than that in mixture layer 1 B may be further disposed between current collector 1 A and mixture layer 1 B as shown in the sectional view of FIG. 4 .
- conductive material such as acetylene black is preferably added to binding layer 20 .
- Binding layer 20 is produced, for example as: the conductive material is added into the solvent in which first binder 15 is dispersed; the resulting mixture is stirred to obtain a slurry; and then the slurry is applied to current collector 1 A. The above-described negative electrode mixture slurry is applied onto binding layer 20 and dried to produce mixture layer 1 B.
- part of composite negative electrode active material 14 contained in mixture layer 1 B can be moved to binding layer 20 , so that the content of first binder 15 can be made to be higher near current collector 1 A.
- the content of first binder 15 can be made to be higher near current collector 1 A. In this way, silicon-containing particles 11 are more firmly and rightly bound to current collector 1 A.
- first binder 15 When the content of first binder 15 is less than 1 part by weight with respect to 100 parts by weight of silicon-containing particles 11 , repetition of charge-discharge (expansion and contraction) makes loose the binding between mixture layer 1 B and current collector 1 A and makes mixture layer 1 B easy to peel off. In other words, the cycle characteristics are degraded.
- first binder 15 exceeds 30 parts by weight with respect to 100 parts by weight of silicon-containing particles 11 , first binder 15 excessively covers silicon-containing particles 11 . Ion conductivity in the negative electrode is reduced, and the high-load discharge characteristics degrade. Therefore, the content of first binder 15 is preferably 1 part by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the silicon-containing particles.
- Second binder 16 When the content of second binder 16 is less than 3 parts by weight with respect to 100 parts by weight of CNFs, binding between each assembly of composite negative electrode active material 14 is insufficient in mixture layer 1 B, whereby repetition of charge-discharge (expansion and contraction) makes loose the binding between each assembly of the composite electrode active material in mixture layer 1 B, and makes each assembly of composite negative electrode active material 14 easy to peel off from mixture layer 1 B. In other words, the cycle characteristics are degraded. When the content of second binder 16 exceeds 80 parts by weight with respect to 100 parts by weight of CNFs 12 , second binder 16 excessively covers CNFs 12 . Conductivity in the negative electrode is reduced, and the cycle characteristics degrade.
- the content of second binder 16 is preferably 3 parts by weight or more and 80 parts by weight or less with respect to 100 parts by weight of CNFs 12 .
- the mixing ratios of both kinds of binders are set to be in the above-mentioned ranges, a non-aqueous electrolyte secondary battery having high cycle characteristics and high high-load discharge characteristics is obtained.
- a producing procedure of composite negative electrode active material 14 of sample 1 is described.
- a predetermined amount of silicon oxide SiO particles, average particle diameter is 10 ⁇ m or less
- SiO particles average particle diameter is 10 ⁇ m or less
- a solution dissolving 1 g iron nitrate nonahydrate in 100 g ion-exchanged water According to gravimetric analysis (JIS Z2613) for the SiO particles, O/Si molar ratio is 1.01.
- water is removed from it with an evaporator so as to deposit iron nitrate on the surfaces of the SiO particles.
- the SiO particles loaded with iron nitrate are put in a ceramic reaction vessel and heated to 500° C. in a helium gas atmosphere.
- the helium gas is replaced by a gas composed of 50 vol % hydrogen gas and 50 vol % carbon monoxide gas, and the SiO particles are heated at 500° C. for one hour so as to grow flat CNFs 12 with a diameter of about 80 nm and a length of about 50 ⁇ m.
- the mixture gas is replaced by helium gas, and the inside of the reaction vessel is cooled to room temperature so as to obtain composite negative electrode active material 14 .
- the content of thus grown CNFs 12 is 25 parts by weight with respect to 100 parts by weight of SiO particles.
- a negative electrode mixture slurry is prepared by homogenously mixing and dispersing the following materials:
- the resulting negative electrode mixture slurry is applied to a 14 ⁇ M thick copper (Cu) foil as current collector 1 A and dried in a manner that the electrode plate thickness after drying becomes 100 ⁇ m.
- the plate is stamped into a square having sides of 11 mm to obtain negative electrode 1 .
- a flat model cell is formed of negative electrode 1 thus produced, a square metallic lithium foil having a thickness of 300 ⁇ m and sides of 13 mm as counter electrode 2 , and a polyethylene microporous film having a thickness of 20 ⁇ m and a porosity of about 40% as separator 3 .
- the model cell is inserted into laminate bag 4 .
- laminate bag 4 is sealed.
- the designed capacity (C, in mAh) of the obtained model cell of sample 1 is 5 mAh.
- the model cells of samples 2 to 7 are produced similarly to sample 1, except that mixing ratios of polyacrylic acid that is used as first binder 15 in sample 1, with respect to 100 parts by weight of composite negative electrode active material 14 , are set at 0.4, 0.7, 3.8, 15, 22.5, and 28 parts by weight, respectively, in producing each composite negative electrode active material 14 and each negative electrode 1 for samples 2 to 7.
- mixing ratios of first binder 15 with respect to 100 parts by weight of SiO are 0.5, 1, 5, 20, 30, and 37.3 parts by weight, respectively.
- the model cells of samples 8 to 13 are produced similarly to sample 1, except that mixing ratios of BM-400B that is used as binder 16 in sample 1, with respect to 100 parts by weight of composite negative electrode active material 14 , are set at 0.4, 0.8, 2.5, 15, 20, and 24 parts by weight, respectively, in producing each composite negative electrode active material 14 and each negative electrode 1 for samples 8 to 13.
- mixing ratios of second binder 16 are 3, 10, 60, 80, and 96 parts by weight, respectively, with respect to 100 parts by weight of CNFs 12 .
- CNFs 12 are grown on the surfaces of SiO particles similarly to sample 1 except that the reaction time is set at 80 minutes. Extending the reaction time increases the content of CNFs 12 to 30 parts by weight with respect to 100 parts by weight of SiO.
- the model cell of sample 14 is produced similarly to sample 1, except that 9.5 parts by weight of polyacrylic acid as first binder 15 and 9.5 parts by weight of BM-400B as second binder 16 are added with respect to 100 parts by weight of composite negative electrode active material 14 .
- the mixing ratio of first binder 15 is 13.6 parts by weight with respect to 100 parts by weight of SiO.
- the mixing ratio of second binder 16 is 31.7 parts by weight with respect to 100 parts by weight of CNFs 12 .
- the model cell of sample 15 is produced similarly to sample 1 except that copper foil as current collector 1 A is sandblasted and the surface thereof is roughened so that surface roughness R a is increased from 0.1 ⁇ m to 1 ⁇ m.
- sample 16 two kinds of negative electrode mixture slurries are used.
- First slurry of sample 16 is prepared similarly to the negative electrode mixture slurry of sample 1 except that the mixing ratio of polyacrylic acid as first binder 15 is set at 0.7 parts by weight with respect to 100 parts by weight of obtained composite negative electrode active material 14 .
- the mixing ratio of first binder 15 is 1 part by weight with respect to 100 parts by weight of SiO.
- second slurry of sample 16 is prepared similarly to the negative electrode mixture slurry of sample 1 except that the mixing ratio of polyacrylic acid is set at 22.4 parts by weight with respect to 100 parts by weight of composite negative electrode active material 14 .
- the mixing ratio of first binder 15 is 30 parts by weight with respect to 100 parts by weight of SiO.
- the second slurry is firstly applied to copper foil as current collector 1 A so that the thickness after drying is 43 ⁇ m to form a lower layer, and the first slurry is then applied to the second slurry so that the thickness after drying is 43 ⁇ m to form an upper layer. Except for this condition, the model cell of sample 16 is produced similarly to sample 1.
- binding layer 20 is formed on current collector 1 A.
- 20 parts by weight of polyacrylic acid as first binder is mixed with 100 parts by weight of acetylene black, and a third slurry is produced using distilled water as a solvent.
- the third slurry is applied to copper foil as current collector 1 A so that the thickness after drying is 5 ⁇ m, and the same slurry as the negative electrode mixture slurry used for sample 1 is then applied and dried, thereby forming binding layer 20 .
- the model cell of sample 17 is produced similarly to sample 1.
- Initial charge capacity and initial discharge capacity of each model cell of samples 1 to 17 thus produced are measured at a charge-discharge current of 0.1 CmA.
- the discharge capacity thus measured is converted into a value per unit volume (1 cm 3 ) of mixture layer 1 B to obtain and discharge capacity density is calculated.
- the cell is charged until the voltage across the electrodes reaches 0 V, and the cell is discharged until the voltage reaches 1.5 V.
- 0.1 CmA indicates a current value obtained by dividing the designed capacity of batteries by 10 hours.
- each model cell of samples 1 to 17 is then evaluated.
- Each model cell is charged at a current of 0.1 CmA, and then discharged at a current of 0.5 CmA so as to obtain the discharge capacity at 0.5 CmA.
- the discharge capacity thus obtained is divided by the discharge capacity at 0.1 CmA to estimate the capacity retention rate, which is used as an index of the high-load characteristics.
- charge-discharge cycle characteristics are evaluated. Charge and discharge are repeated under the same conditions as the initial capacity measurement. The rest time between each charge and discharge is set at 20 minutes. In the discharge state after five cycles, each model cell of samples 1 to 17 is disassembled, and mixture layer 1 B is observed to see whether peeling or separation occurs. The charge-discharge cycle is repeated for each model cell. The cycle number until the discharge capacity reaches 60% of the initial discharge capacity is used as an index of the cycle characteristics of each model cell.
- the evaluation standard of the capacity retention rate is set at 60% or more.
- the evaluation standard of the cycle number is set at 50 cycles or more in consideration of practicality.
- Table 1 shows the composition of each negative electrode of samples 1 to 17 and evaluation results of the characteristics of each model cell.
- the model cells of samples 1 to 17 using negative electrodes that contain first binder 15 composed of an acryl-group-containing polymer and second binder 16 composed of adhesive rubber particles have sufficient high-load discharge characteristics and sufficient cycle characteristics.
- the model cells of sample 1, samples 3 to 6, samples 9 to 12, and samples 14, 15, 16 and 17 having negative electrodes that contain the first binder and second binder at an adequate mixing ratio exhibit excellent high-load discharge characteristics and excellent cycle characteristics.
- current collector 1 A has an increased area for the adsorption of first binder 15 having a high affinity to current collector 1 A, and hence the binding property is further increased and the cycle characteristics are further improved.
- sample 16 the content of first binder 15 having a high affinity to current collector 1 A is set higher near current collector 1 A, so that peeling of mixture layer 1 B from current collector 1 A caused by rapid expansion and contraction of SiO is significantly reduced and cycle characteristics are further improved.
- binding layer 20 containing first binder 15 is disposed on current collector 1 A, and mixture layer 1 B is stuck to current collector 1 A. Therefore, cycle characteristics are further improved similarly to sample 16.
- composition of CNFs 12 and SiO of silicon-containing particles 11 in composite negative electrode active material 14 is changed.
- a negative electrode for non-aqueous electrolyte secondary batteries having excellent cycle characteristics and excellent high-load discharge characteristics is also obtained.
- sample 2 where the content of first binder 15 is less than 1 part by weight with respect to 100 parts by weight of SiO, the cycle characteristics are low. This is probably because repetition of charge and discharge (expansion and contraction) makes loose the binding between mixture layer 1 B and current collector 1 A and makes mixture layer 1 B easy to peel off. When the model cell is disassembled and inspected after evaluating the characteristics thereof, peeling is actually observed.
- sample 7 where the content of first binder 15 exceeds 30 part by weight with respect to 100 parts by weight of SiO, the high-load discharge characteristics are low. That is probably because excessively covering silicon-containing particles 11 with first binder 15 reduces the ion conductivity.
- the advantages of the present invention have been described with reference to specific experiments using the model cells having a structure of FIG. 1 and their results.
- a positive electrode capable of charging and discharging lithium ions is used instead of metallic lithium used as counter electrode 2
- a laminate type non-aqueous electrolyte secondary battery sealed in laminate bag 4 can be obtained.
- the positive electrode has a mixture layer containing, as a positive electrode active material, a lithium-containing compound such as LiCoO 2 , LiNiO 2 , Li 2 MnO 4 , a mixture of them, or a composite oxide of them.
- Such a positive electrode active material reduces lithium ions at least during discharge, and contains lithium ions in an uncharged state.
- negative electrode 1 In a structure where negative electrode 1 does not contain lithium in an uncharged state, the positive electrode needs to contain lithium ions as in the present case.
- negative electrode 1 having the structure as described above is used in a non-aqueous electrolyte secondary battery having this structure, a battery having sufficient high-load characteristics and sufficient cycle characteristics is achieved.
- the conductive agent to be used for the positive electrode include the following materials: graphites such as natural graphite and artificial graphite; carbon blacks such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; metal powders such as aluminum powder; conductive whiskers such as zinc oxide whisker and potassium titanate whisker; conductive metal oxides such as titanium oxide; and organic conductive materials such as a phenylene derivative.
- binder for the positive electrode examples include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethylacrylate ester, polyethylacrylate ester, polyhexylacrylate ester, polymethacrylic acid, polymethyl methacrylate ester, polyethylmethacrylate ester, polyhexyl methacrylate ester, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, and carboxymethyl cellulose.
- PVDF polyvinylidene fluoride
- aramid resin polyamide
- polyimide polyamideimide
- polyacrylonitrile polyacrylic acid
- polymethylacrylate ester polyethylacrylate ester,
- binder examples include copolymers containing at least two selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkylvinylether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethylvinylether, acrylic acid, and hexadiene.
- copolymers containing at least two selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkylvinylether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethylvinylether, acrylic acid, and hexadiene.
- two or more of these copolymers can be mixed.
- the current collector and the lead used for the positive electrode can be made of stainless steel, aluminum, titanium, carbon, conductive resin, or the like. These materials may be surface-treated with carbon, nickel, titanium or the like.
- the structure of the battery is not limited to the aforementioned laminate-type battery structure in which rectangular positive and negative electrode plates face each other.
- a coin-shaped battery structure where circular positive and negative electrode plates face each other, a cylindrical battery structure where thin and long positive and negative electrodes are wound, or a prismatic battery structure can be used. Any of these structures provides the same advantages as the laminate-type battery structure.
- Coin-shaped batteries do not always need current collector 1 A, and mixture layer 1 B may be formed directly on the inner surface of a metal case which is made of iron, nickel-plated iron, or the like and also serves as an external terminal.
- the composite negative electrode active material may be mixed with a powdered binder and then pressed.
- a negative electrode for non-aqueous electrolyte secondary batteries related to the present invention can provide a high-capacity non-aqueous electrolyte secondary battery having improved high-load discharge characteristics and cycle characteristics.
- the negative electrode contributes to the increase in energy density of lithium batteries expected to have growing demand.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Inorganic Chemistry (AREA)
- Composite Materials (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Cell Electrode Carriers And Collectors (AREA)
- Secondary Cells (AREA)
Abstract
Description
- The present invention relates to a negative electrode for non-aqueous electrolyte secondary batteries, and more particularly to a technology for extending the life of a negative electrode using a composite negative electrode active material containing silicon-containing particles as active material cores.
- With the advancement of portable and cordless electronic instruments, growing expectation has been directed to non-aqueous electrolyte secondary batteries smaller in size, lighter in weight, and higher in energy density. In non-aqueous electrolyte secondary batteries, carbon materials such as graphite are used as a negative electrode active material in practical applications. However, carbon materials have a theoretical capacity density of as low as 372 mAh/g. In order to increase the energy density of non-aqueous electrolyte secondary batteries, an attempt has been made where as the negative electrode active material are used silicon (Si), tin (Sn), germanium (Ge), an oxide thereof, and an alloy thereof which can form alloys with lithium. These materials have a higher theoretical capacity density than carbon materials. In particular, silicon-containing particles such as silicon particles and silicon oxide particles have been widely studied because they are less expensive.
- However, when these materials are used as a negative electrode active material and are subjected to repeated charging and discharging, the particles of the negative electrode active material change their volume. This change in volume causes the active material particles to be collapsed into fine particles, thereby lowering the conductivity among the particles. As a result, satisfactory charge-discharge cycle characteristics (hereinafter, cycle characteristics) are not attained.
- Japanese Patent Unexamined Publication No. 2004-349056, for example, discloses a technology using composite particles (composite negative electrode active material) produced as follows: active material particles containing metal or semimetal that can form lithium alloys are used as the cores (active material cores), and a plurality of carbon fibers are bound to each of the active material cores. It has been reported that this structure can ensure the conductivity even if the active material particles change in volume, thereby maintaining sufficient cycle characteristics. Negative electrodes having high capacity and high functionality are considered to be structured, for example, by using a technology for adequately combining binders that are disclosed in Japanese Patent Unexamined Publication No. H11-354126, in addition to the former technology.
- However, only by mixing a plurality kinds of binders, it is difficult to avoid such an accident that a mixture layer containing the composite negative electrode active material is peeled off from a negative electrode current corrector by an action of stress generated when the composite negative electrode active material expands and contracts. It is also difficult to prevent the composite negative electrode active material from dropping off from the mixture layer. This is probably because the surface physical property of silicon-containing particles is different from that of carbon fibers. Negative electrodes having a mixture layer with sufficient binding force are difficult to be produced only by mixing a plurality kinds of binders without considering these surface physical properties.
- The present invention provides a negative electrode for non-aqueous electrolyte secondary batteries having high cycle characteristics, and a non-aqueous electrolyte secondary battery having the negative electrode. In the negative electrode, the increase in impedance of the whole negative electrode is suppressed by maintaining the binding force among composite negative electrode active materials in a mixture layer, and also by maintaining the binding force between the mixture layer and a current collector. The negative electrode for non-aqueous electrolyte secondary batteries of the present invention has a current collector and a mixture layer. The mixture layer contains a composite negative electrode active material, a first binder, and a second binder. The mixture layer is formed on the current collector. The composite negative electrode active material contains a silicon-containing particle capable of charging and discharging at least lithium ions, a carbon nanofiber (hereinafter, CNF), and a catalyst element. The CNF is attached to the surfaces of the silicon-containing particle. The catalyst element is at least one selected from the group consisting of copper (Cu), iron (Fe), cobalt (Co), nickel (Ni), molybdenum (Mo) and manganese (Mn), and promotes the growth of the CNF. The first binder is composed of an acryl-group-containing polymer. The second binder is composed of an adhesive rubber particle. The first binder binds the silicon-containing particle to the current collector, and the second binder binds CNFs together. The first binder has a high affinity to the silicon-containing particle, and the second binder has a high affinity to the CNF. Similarly to the silicon-containing particle, the current collector has a high affinity to the first binder. Each composite negative electrode active material containing the CNF is bound together by the second binder, and the composite negative electrode active material is bound to the current collector through intermediately existing chemical bonds provided by the first binder. Binding in the mixture layer and binding of the mixture layer to the current collector become tight. Therefore, even if the silicon-containing particles expand and contract during charge and discharge, the conductive structure in the mixture layer and the conductive structure between the mixture layer and the current collector are kept. As a result, the cycle characteristics are improved.
- The present invention further provides a non-aqueous electrolyte secondary battery employing a negative electrode containing the aforementioned composite negative electrode active material.
-
FIG. 1 is a transparent plan view showing a structure of a model cell in accordance with a first exemplary embodiment of the present invention. -
FIG. 2 is a sectional view of the model cell shown inFIG. 1 taken along line A-A. -
FIG. 3 is a schematic sectional view showing a structure of a mixture layer near a current collector of a negative electrode for non-aqueous electrolyte secondary batteries in accordance with the first exemplary embodiment of the present invention. -
FIG. 4 is a sectional view showing another structure of the negative electrode for non-aqueous electrolyte secondary batteries in accordance with the first exemplary embodiment of the present invention. -
-
- 1 negative electrode
- 1A current collector
- 1B mixture layer
- 1C lead
- 2 counter electrode
- 2A current collector
- 2C lead
- 3 separator
- 4 laminate bag
- 5 non-aqueous electrolyte
- 7 modified polypropylene film
- 11 silicon-containing particle
- 12 carbon nanofiber
- 13 catalyst element
- 14 composite negative electrode active material
- 15 first binder
- 16 second binder
- 20 binding layer
- An exemplary embodiment of the present invention will be described hereinafter with reference to drawings. The present invention is not limited to the following description except for its fundamental features.
-
FIG. 1 is a transparent plan view showing the structure of a model cell produced to evaluate a negative electrode for non-aqueous electrolyte secondary batteries of the first exemplary embodiment of the present invention.FIG. 2 is a cross sectional view taken alongline 1B-1B.FIG. 3 is a schematic diagram showing a structure of a mixture layer near a current collector. -
Negative electrode 1 shown inFIGS. 1 and 2 hasmixture layer 1B that is disposed oncurrent collector 1A and electrically connected tocurrent collector 1A. As shown inFIG. 3 ,mixture layer 1B contains an assembly of composite negative electrodeactive material 14. Each assembly of composite negative electrodeactive material 14 contains a silicon-containingparticle 11 capable of charging and discharging lithium ions, and a number of carbon nanofibers (hereinafter, CNFs) 12 attached to silicon-containingparticle 11.CNFs 12 are grown using, as a core,catalyst element 13 which is dispersed and supported on the surface of silicon-containingparticle 11.Catalyst element 13 is at least one selected from the group consisting of copper (Cu), iron (Fe), cobalt (Co), nickel (Ni), molybdenum (Mo), and manganese (Mn), and promotes the growth ofCNFs 12.Mixture layer 1B further containsfirst binder 15 composed of an acryl-group-containing polymer andsecond binder 16 composed of adhesive rubber particles.First binder 15 binds silicon-containingparticle 11 tocurrent collector 1A, andsecond binder 16 binds CNFs 12 together. -
Counter electrode 2 made of metallic lithium is faced tonegative electrode 1 viaseparator 3.Current collector 2A is bonded to counterelectrode 2 on the side opposite toseparator 3. These components are accommodated inlaminate bag 4.Laminate bag 4 is also filled withnon-aqueous electrolyte 5 and sealed. In other words,non-aqueous electrolyte 5 is interposed betweennegative electrode 1 andcounter electrode 2.Current collectors leads Leads polypropylene film 7 placed at the opening oflaminate bag 4, so thatlaminate bag 4 is sealed. - Next, composite negative electrode
active material 14 is described in detail. Silicon-containingparticle 11 can be made of Si or SiOx (where, 0.05≦x≦1.95, preferably 0.3≦x≦1.3), or can be made of an alloy, a compound, a solid solution or the like in which Si is partly replaced with at least one element selected from B, Mg, Ni, Ti, Mo, Co, Ca, Cr, Cu, Fe, Mn, Nb, Ta, V, W, Zn, C, N, and Sn. - Silicon-containing
particles 11 may be composed of one kind or a plurality kinds of the above-mentioned materials. Examples of silicon-containingparticles 11 composed of the plurality kinds include a compound containing silicon, oxygen, and nitrogen, and a composite of a plurality of compounds containing silicon and oxygen in different ratios. Thus, silicon-containingparticles 11 contain at least one selected from the group consisting of pure silicon, a silicon-containing alloy, a silicon-containing compound, and a silicon-containing solid solution. The shapes and kinds of silicon-containingparticles 11 and magnitudes of the expansion and contraction are not especially limited. Of these, SiOx is desirable because its discharge capacity density is large and its expansion coefficient during charge is smaller than that of pure silicon. -
CNFs 12 attach to the surface of each silicon-containingparticle 11 where they start to grow. In other words,CNFs 12 attach directly to the surface of silicon-containingparticle 11 without a binder therebetween. In some growing conditions,CNFs 12 may be chemically bonded to the surface of silicon-containingparticle 11 at least at one end thereof which is the starting point of the growth. This reduces the resistance to current collection and assures high electronic conductivity in the battery, thereby providing sufficient charge-discharge characteristics. In a case whereCNFs 12 attach to silicon-containingparticle 11 viacatalyst element 13,CNFs 12 hardly become detached from silicon-containingparticle 11. Therefore,negative electrode 1 becomes more resistant to a rolling load, namely a mechanical load that is applied to the negative electrode when the negative electrode is rolled to increase filling density thereof. - In order to allow
catalyst element 13 to exhibit sufficient catalytic activity untilCNFs 12 are fully grown,catalyst element 13 is preferably present in a metallic state in the surface parts of silicon-containingparticles 11.Catalyst element 13 is preferably present in the form of metal particles having a diameter of 1 nm to 1000 nm, for example. On the other hand, when the growth ofCNFs 12 is complete, the metal particles ofcatalyst element 13 are preferably oxidized. -
CNFs 12 have a fiber length of preferably 1 nm to 1 mm, and more preferably 500 nm to 100 μm. When the fiber length is less than 1 nm, the effect to increase electrode conductivity is too small. In contrast, the fiber lengths of over 1 mm tend to reduce the active material density or capacity of the electrode. Although not limited,CNFs 12 are preferably in the form of at least one selected from the group consisting of tube-shaped carbon, accordion-shaped carbon, plate-shaped carbon, and herringbone-shaped carbon.CNFs 12 may absorbcatalyst element 13 during their growth.CNFs 12 have a fiber diameter of preferably 1 nm to 1000 nm, and more preferably 50 nm to 300 nm. -
Catalyst element 13 in a metallic state works as an active site to growCNFs 12. More specifically,CNFs 12 start to grow when silicon-containingparticles 11 havingcatalyst element 13 that is exposed in a metallic state on their surfaces are introduced into a high-temperature atmosphere containing the source gas ofCNFs 12. When silicon-containingparticles 11 have nocatalyst element 13 on their surfaces,CNFs 12 do not grow. - Methods for forming metal particles composed of
catalyst element 13 on the surfaces of silicon-containingparticles 11 are not particularly limited; however, one preferable method is to support metal particles on the surfaces of silicon-containingparticles 11. - When the metal particles are supported in this method, it is possible to mix silicon-containing
particles 11 with the metal particles in solid form; however, it is preferable to soak silicon-containingparticles 11 in a solution dissolving a metal compound serving as the source material of the metal particles in an appropriate solvent. After silicon-containingparticles 11 are soaked in the solution, the solvent is removed from silicon-containingparticles 11, and then they are heated if necessary. In this way, can be obtained silicon-containingparticles 11 which support, on their surfaces, metal particles composed ofcatalyst element 13 having a diameter of 1 nm to 1000 nm, preferably 10 nm to 100 nm, in a highly and uniformly dispersed state. - It is difficult to form the metal particles of
catalyst element 13 having a diameter of less than 1 nm. When the diameter exceeds 1000 nm, the metal particles are extremely uneven in size, makingCNFs 12 difficult to grow. It is therefore difficult to form a highly conductive negative electrode. In this way, the diameter of the metal particles ofcatalyst element 13 is preferably 1 nm or more and 1000 nm or less. - Specific examples of the metal compound to provide the aforementioned solution include nickel nitrate, cobalt nitrate, iron nitrate, copper nitrate, manganese nitrate, and hexaammonium heptamolybdate tetrahydrate. The solvent used for the solution can be appropriately selected from water, an organic solvent, and a mixture of water and an organic solvent, in consideration of the solubility of the metal compound and the compatibility of the compound with the electrochemical active phases contained in silicon-containing
particles 11. The electrochemical active phases mean, of crystal phases or amorphous phases composing silicon-containingparticles 11, the crystal phases or amorphous phases metallic phases and metallic oxide phases that allow an oxidation-reduction reaction accompanied by electron transfer, namely a battery reaction. Specific examples of the organic solvent include ethanol, isopropyl alcohol, toluene, benzene, hexane, and tetrahydrofuran. - Alternatively, it is also possible to synthesize alloy particles containing
catalyst element 13 and to use them as silicon-containingparticles 11. In this case, alloys of silicon andcatalyst element 13 are synthesized by a common alloying method. The silicon element reacts electrochemically with lithium to form alloys, thereby forming the electrochemical active phases. The metallic phases ofcatalyst element 13 are at least partly exposed in the form of particles having a diameter of 10 nm to 100 nm, for example, on the surfaces of the alloy particles. - The content of the metal particles or metallic phases of
catalyst element 13 is preferably 0.01 wt % to 10 wt % of silicon-containingparticles 11, more preferably 1 wt % to 3 wt %. When the content of the metal particles or the metallic phases is too low, it takes a lot of time to growCNFs 12, thereby decreasing production efficiency. In contrast, when the content is too high,catalyst element 13 agglomerates and growsCNFs 12 uneven and having large fiber diameters. This leads to decrease in conductivity and active material density ofmixture layer 1B. This also leads to relative decrease in the proportion of the electrochemical active phases, making it difficult to use composite negative electrodeactive material 14 as a high-capacity electrode material. - The following is a description of a method for producing composite negative electrode
active material 14 composed of silicon-containingparticles 11,CNFs 12, andcatalyst element 13. This production method includes the following four steps of (a) to (d). - (a) A step of
loading catalyst element 13 at least in the surface parts of silicon-containingparticles 11 which can charge and discharge lithium ions.Catalyst element 13 is at least one selected from Cu, Fe, Co, Ni, Mo, and Mn, and promotes the growth ofCNFs 12. - (b) A step of growing
CNFs 12 on the surface of silicon-containingparticle 11 in an atmosphere containing carbon-containing gas and hydrogen gas. - (c) A step of sintering silicon-containing
particles 11 withCNFs 12 attached thereto in an inert gas atmosphere at 400° C. or higher and 1600° C. or lower. - (d) A step of crushing silicon-containing
particle 11 withCNFs 12 attached thereto to adjust the tap density thereof to 0.42 g/cm3 or more and 0.91 g/cm3 or less. - After Step (c), composite negative electrode
active material 14 may be subjected to heat treatment in the air at 100° C. or higher and 400° C. or lower to oxidizecatalyst element 13. The heat treatment at this temperature range can oxidizeonly catalyst element 13 without oxidizingCNFs 12. - The method of
loading catalyst element 13 on the surfaces of silicon-containingparticles 11 at Step (a) is not limited especially. However, there may be mentioned, a step of supporting the metal particles ofcatalyst element 13 on the surfaces of silicon-containingparticles 11, a step of reducing the surfaces of silicon-containingparticles 11 containingcatalyst element 13, a step of synthesizing alloy particles of silicon andcatalyst element 13, and other steps. - The following is a description of conditions when
CNFs 12 are grown on the surfaces of silicon-containingparticles 11 at Step (b).CNFs 12 start to grow when silicon-containingparticle 11 havingcatalyst element 13 at least in the surface part thereof is introduced into a high-temperature atmosphere containing the source gases ofCNFs 12. For example, silicon-containingparticles 11 are put in a ceramic reaction vessel and heated to high temperatures of 100° C. to 1000° C., preferably to 300° C. to 600° C., in an inert gas or a gas having a reducing power. Then, carbon-containing gas and hydrogen gas, which are the source gases ofCNFs 12, are introduced into the reaction vessel. When the temperature in the reaction vessel is lower than 100° C.,CNFs 12 either do not grow or grow very slowly, thereby damaging the productivity. In contrast, when the temperature in the reaction vessel exceeds 1000° C., the source gases are decomposed rapidly to make it harder to growCNFs 12. - The source gases are preferably a mixture gas of carbon-containing gas and hydrogen gas. Specific examples of the carbon-containing gas include methane, ethane, ethylene, butane, and carbon monoxide. The molar ratio (volume ratio) of the carbon-containing gas in the mixture gas is preferably 20% to 80%. When
catalyst element 13 in a metallic state is not exposed on the surfaces of silicon-containingparticles 11, the reduction ofcatalyst element 13 and the growth of CNFs 12 can be performed in parallel by regulating the hydrogen gas at a high proportion in the mixture gas. When the growth ofCNFs 12 is terminated, the mixture gas of the carbon-containing gas and hydrogen gas is replaced with an inert gas, and the inside of the reaction vessel is cooled to room temperature. - Next, in Step (c), silicon-containing
particles 11 havingCNFs 12 attached thereto are sintered in an inert gas atmosphere at 400° C. or higher and 1600° C. or lower. This sintering is preferable because it can improve crystallinity ofCNFs 12, suppress the irreversible reaction which progresses at the initial charge of the battery betweenelectrolyte 5 andCNFs 12, and hence achieve excellent charge-discharge efficiency of the battery. When such sintering process is either not performed or performed at a temperature lower than 400° C., the irreversible reaction may not be suppressed, decreasing the charge-discharge efficiency of the battery. In contrast, when sintering temperatures exceed 1600° C., the electrochemical active phases of silicon-containingparticles 11 react withCNFs 12 and may be inactivated or reduced, so that the charge-discharge capacity of the battery may be decreased. For example, when the electrochemical active phases of silicon-containingparticles 11 are made of silicon, the silicon reacts withCNFs 12 to generate inert silicon carbide, thereby decreasing the charge-discharge capacity of the battery. When silicon-containingparticles 11 are made of silicon, the sintering temperature is particularly preferably 1000° C. or higher and 1600° C. or lower. Some growth conditions of Step (b) can achieveCNFs 12 of high crystallinity. Improving the crystallinity ofCNFs 12 suppresses the irreversible reaction betweenelectrolyte 5 andCNFs 12, as discussed above. In the case whereCNFs 12 of high crystallinity are obtained at Step (b), Step (c) is not always necessary. - After being sintered in the inert gas, composite negative electrode
active material 14 is preferably heat-treated in the air at 100° C. or higher and 400° C. or lower in order to oxidize at least parts (surfaces, for example) of the metal particles or metallic phases ofcatalyst element 13. When the heat-treatment temperature is lower than 100° C., it is difficult to oxidize the metal. When the temperature exceeds 400° C., grownCNFs 12 may burn. - In Step (d), sintered silicon-containing
particles 11 withCNFs 12 attached thereto are crushed. Crushing is preferred, because composite negative electrodeactive material 14 of sufficient filling property is obtained. However, when the tap density of the particles is 0.42 g/cm3 or more and 0.91 g/cm3 or less without crushing, crushing is not always necessary. In other words, when silicon-containing particles with sufficient filling property are used as a source material, Step (d) is not always necessary. - The following is a description of a method for producing
negative electrode 1. Composite negative electrodeactive material 14 composed of silicon-containingparticles 11 havingCNFs 12 on their surfaces are mixed withfirst binder 15,second binder 16, and a solvent to prepare a negative electrode mixture slurry. -
First binder 15 is a polymer containing an acryl group as described above. Specifically, an example offirst binder 15 includes polyacrylic acid, polyacrylic ester, polymethacrylic acid, and polymethacrylic ester. Especially, polyacrylic acid and polymethacrylic acid that contain a carboxyl group are preferable because the hydrogen atom contained in the carboxyl group form hydrogen bond with metallic atoms to provide a high binding force. -
Second binder 16 is an adhesive rubber particle. An example ofsecond binder 16 includes styrene-butadiene copolymer (SBR). Especially, core-shell-type modified SBR that is designed so that the core has elasticity and the shell has adhesion is more preferable. - Examples of the solvent include N-methyl-2-pyrrolidone (NMP) and water.
- The obtained slurry is applied to both surfaces of
current collector 1A using a doctor blade, and dried, thereby formingmixture layer 1B oncurrent collector 1A. At this time, appropriate adjustment of the drying condition can provide a structure wherefirst binder 15 binds silicon-containingparticles 11 tocurrent collector 1A, andsecond binder 16 binds CNFs 12 together. Specifically, the temperature and air flow are adjusted during drying.Second binder 16 having the property of moving with evaporating solvent accumulate more on the portion ofmixture layer 1B relatively close to the surface thereof as compared with the vicinity ofcurrent collector 1A. As a result, a structure wherefirst binder 15 binds silicon-containingparticles 11 tocurrent collector 1A is obtained. - Then,
mixture layer 1B is rolled to adjust its thickness. The obtained long strip of negative electrode is either stamped or cut into a predetermined size. Lead 8 made of nickel or copper is connected to the exposed part ofcurrent collector 1A, for example by welding or the other methods, to completenegative electrode 1. -
Current collector 1A can be a metal foil made of stainless steel, nickel, copper, or titanium, or a thin film made of carbon or a conductive resin.Current collector 1A may also be surface-treated with carbon, nickel, titanium, or the like. - Examples of
nonaqueous electrolyte 5 can include an electrolyte solution dissolving a solute in an organic solvent and a polymer electrolyte where the electrolyte solution is immobilized with a polymer. When the electrolyte solution is used, it is desirable thatseparator 3 be interposed betweencounter electrode 2 andnegative electrode 1 and is impregnated with the electrolyte solution.Separator 3 is formed of non-woven fabric or micro porous film made of polyethylene, polypropylene, aramid resin, amide-imide, polyphenylene sulfide, or polyimide. The inside or surface ofseparator 3 may contain a heat-resistant filler such as alumina, magnesia, silica, and titania. Besidesseparator 3, a heat-resistant layer that is made of these fillers and the same binder as that used in the electrode may be disposed. - The material of
nonaqueous electrolyte 5 is selected based on oxidation-reduction potential of active material, and others. Examples of the solute preferably used innonaqueous electrolyte 5 include the following materials: LiPF6; LiBF4; LiCiO4; LiAlCl4; LiSbF6; LiSCN; LiCF3SO3; LiCF3CO2; LiAsF6; LiB10Cl10; lower aliphatic lithium calboxylate; LiF; LiCl; LiBr; LiI; chloroborane lithium; various borates such as bis(1,2-benzendiolate (2-)-O,O′) lithium borate, bis(2,3-naphthalenediolate (2-)-O,O′) lithium borate, bis(2,2′-biphenyldiolate (2-)-O,O′) lithium borate, and bis(5-fluoro-2-olate-1-benzensulfonic acid-O,O′) lithium borate; and various salts generally used in a lithium battery such as (CF3SO2)2NLi, LiN(CF3SO2)(C4F9SO2), (C2F5SO2)2NLi, and tetraphenyl lithium borate. - The organic solvent for dissolving the solute is a solvent generally used in a lithium battery such as one or a mixture of the following solvents: ethylene carbonate; propylene carbonate; butylene carbonate; vinylene carbonate; dimethyl carbonate; diethyl carbonate; ethyl methyl carbonate; dipropyl carbonate; methyl formate; methyl acetate; methyl propionate; ethyl propionate; dimethoxymethane; γ-butyrolactone; γ-valerolactone; 1,2-diethoxyethane; 1,2-dimethoxyethane; ethoxymethoxyethane; trimethoxymethane; tetrahydrofuran derivatives such as tetrahydrofuran and 2-methyl-tetrahydrofuran; dimethyl sulfoxide; dioxolane derivatives such as 1,3-dioxolane and 4-methyl-1,3-dioxolane; formamide; acetamide; dimethylformamide; acetonitrile; propylnitrile; nitromethane; ethylmonoglyme; triester phosphate; acetate ester; propionate ester; sulfolane; 3-methyl-sulfolane; 1,3-dimethyl-2-imidazolidinone; 3-methyl-2-oxazolidinone; a propylene carbonate derivative; ethyl ether; diethyl ether; 1,3-propane sultone; anisole; and fluorobenzene.
- The solvent may further contain an additive such as vinylene carbonate, cyclohexylbenzene, biphenyl, diphenyl ether, vinylethylene carbonate, divinylethylene carbonate, phenylethylene carbonate, diallyl carbonate, fluoroethylene carbonate, catechol carbonate, vinyl acetate, ethylene sulfite, propanesultone, trifluoropropylene carbonate, dibenzofuran, 2,4-difluoroanisole, o-terphenyl, and m-terphenyl.
-
Nonaqueous electrolyte 5 may be used in the form of solid polymer electrolyte by mixing or dissolving the solute into one or a mixture of the following polymer materials: polyethylene oxide; polypropylene oxide; polyphosphazene; polyaziridine; polyethylene sulfide; polyvinyl alcohol; polyvinylidene fluoride; polyhexafluoropropylene and the like. The solid polymer electrolyte may be used in a gel form by being mixed or dissolved into the above-mentioned organic solvent. The solid electrolyte made of an inorganic material such as the following material may be used: lithium nitride; lithium halide; lithium oxoate; Li4SiO4; Li4SiO4—LiI—LiOH; Li3PO4—Li4SiO4; Li2SiS3; Li3PO4—Li2S—SiS2; a phosphorus sulfide compound and the like. -
Laminate bag 4 is made of a sheet produced by laminating a hot-melt resin film such as polyethylene on at least one side of a metal foil such as an aluminum foil. The sheet is processed in a bag shape so that the hot-melt resin film forms the inner surface of the bag. The hot-melt resin film on the inner surface is thermally welded to itself, thereby sealing the inside oflaminate bag 4. - As shown in
FIG. 3 ,mixture layer 1B contains composite negative electrodeactive material 14,first binder 15 composed of an acryl-group-containing polymer, andsecond binder 16 composed of adhesive rubber particles.First binder 15 binds silicon-containingparticles 11 tocurrent collector 1A, andsecond binder 16 binds CNFs 12 together. - When only
first binder 15 composed of an acryl-group-containing polymer are used as a binder, silicon-containingparticles 11 are bound tocurrent collector 1A, but each assembly of composite negative electrodeactive material 14 is hardly bound together. Composite negative electrodeactive material 14 can be therefore apt to separate frommixture layer 1B during charge and discharge. When onlysecond binder 16 composed of adhesive rubber particles is used as a binder, each assembly of composite negative electrodeactive material 14 is bound together viaCNFs 12, but is hardly bound tocurrent collector 1A. A large part ofmixture layer 1B is peeled off fromcurrent collector 1A during charge and discharge. Even whenfirst binder 15 andsecond binder 16 are simply mixed and uniformly dispersed (distributed) inmixture layer 1B, the property of each binder is not sufficiently exhibited and hence a large part ofmixture layer 1B is peeled off fromcurrent collector 1A during charge and discharge. Therefore, it is essential thatfirst binder 15 binds silicon-containingparticles 11 tocurrent collector 1A and thatsecond binder 16 binds CNFs 12 together. - The surface of
current collector 1A is preferably roughened. The area to whichfirst binder 15 having a high affinity tocurrent collector 1A sticks increases, so that the binding property ofcurrent collector 1A improves, and that the cycle characteristics improve. Examples of the roughening method include a sandblast method, plating at a high current density, and chemical etching. It is desirable that the surface obtained by roughening have a roughness of 1 μm or more and 5 μm or less. - For effectively preventing peeling off of
mixture layer 1B fromcurrent collector 1A caused by expansion and contraction of composite negative electrodeactive material 14, it is desirable that the content offirst binder 15 having a high affinity tocurrent collector 1A be made higher nearcurrent collector 1A than in other part inmixture layer 1B. The other part means the positions closer to the surface ofmixture layer 1B. Specifically, several kinds of negative electrode mixture slurry having different contents offirst binder 15 are prepared, and the slurry is applied tocurrent collector 1A in the descending order of the contents offirst binder 15. Thus, the content offirst binder 15 can be made to be higher nearcurrent collector 1A. - Alternatively, binding
layer 20 where the content offirst binder 15 is higher than that inmixture layer 1B may be further disposed betweencurrent collector 1A andmixture layer 1B as shown in the sectional view ofFIG. 4 . For producing a negative electrode having high conductivity, conductive material such as acetylene black is preferably added to bindinglayer 20. Bindinglayer 20 is produced, for example as: the conductive material is added into the solvent in whichfirst binder 15 is dispersed; the resulting mixture is stirred to obtain a slurry; and then the slurry is applied tocurrent collector 1A. The above-described negative electrode mixture slurry is applied ontobinding layer 20 and dried to producemixture layer 1B. After that, by rollingnegative electrode 1, part of composite negative electrodeactive material 14 contained inmixture layer 1B can be moved to bindinglayer 20, so that the content offirst binder 15 can be made to be higher nearcurrent collector 1A. By any of the methods above mentioned, the content offirst binder 15 can be made to be higher nearcurrent collector 1A. In this way, silicon-containingparticles 11 are more firmly and rightly bound tocurrent collector 1A. - When the content of
first binder 15 is less than 1 part by weight with respect to 100 parts by weight of silicon-containingparticles 11, repetition of charge-discharge (expansion and contraction) makes loose the binding betweenmixture layer 1B andcurrent collector 1A and makesmixture layer 1B easy to peel off. In other words, the cycle characteristics are degraded. When the content offirst binder 15 exceeds 30 parts by weight with respect to 100 parts by weight of silicon-containingparticles 11,first binder 15 excessively covers silicon-containingparticles 11. Ion conductivity in the negative electrode is reduced, and the high-load discharge characteristics degrade. Therefore, the content offirst binder 15 is preferably 1 part by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the silicon-containing particles. - When the content of
second binder 16 is less than 3 parts by weight with respect to 100 parts by weight of CNFs, binding between each assembly of composite negative electrodeactive material 14 is insufficient inmixture layer 1B, whereby repetition of charge-discharge (expansion and contraction) makes loose the binding between each assembly of the composite electrode active material inmixture layer 1B, and makes each assembly of composite negative electrodeactive material 14 easy to peel off frommixture layer 1B. In other words, the cycle characteristics are degraded. When the content ofsecond binder 16 exceeds 80 parts by weight with respect to 100 parts by weight ofCNFs 12,second binder 16 excessively coversCNFs 12. Conductivity in the negative electrode is reduced, and the cycle characteristics degrade. Therefore, the content ofsecond binder 16 is preferably 3 parts by weight or more and 80 parts by weight or less with respect to 100 parts by weight ofCNFs 12. When the mixing ratios of both kinds of binders are set to be in the above-mentioned ranges, a non-aqueous electrolyte secondary battery having high cycle characteristics and high high-load discharge characteristics is obtained. - The advantages of the present invention are hereinafter described using specific experiments and their results. In the following
samples 1 to 17, all of the mixing ratios of the binders are represented in terms of solid content. - First, a producing procedure of composite negative electrode
active material 14 ofsample 1 is described. A predetermined amount of silicon oxide (SiO particles, average particle diameter is 10 μm or less) is admixed in a solution dissolving 1 g iron nitrate nonahydrate in 100 g ion-exchanged water. According to gravimetric analysis (JIS Z2613) for the SiO particles, O/Si molar ratio is 1.01. After the mixture of SiO particles and solution is stirred for one hour, water is removed from it with an evaporator so as to deposit iron nitrate on the surfaces of the SiO particles. The SiO particles loaded with iron nitrate are put in a ceramic reaction vessel and heated to 500° C. in a helium gas atmosphere. Then, the helium gas is replaced by a gas composed of 50 vol % hydrogen gas and 50 vol % carbon monoxide gas, and the SiO particles are heated at 500° C. for one hour so as to growflat CNFs 12 with a diameter of about 80 nm and a length of about 50 μm. After that, the mixture gas is replaced by helium gas, and the inside of the reaction vessel is cooled to room temperature so as to obtain composite negative electrodeactive material 14. The content of thus grownCNFs 12 is 25 parts by weight with respect to 100 parts by weight of SiO particles. - Next, a producing procedure of
negative electrode 1 ofsample 1 is described. A negative electrode mixture slurry is prepared by homogenously mixing and dispersing the following materials: -
- composite negative electrode
active material 14, 100 parts by weight; - aqueous solution containing 1% polyacrylic acid (average molecular weight is 150,000) as
first binder 15, 10 parts by weight; - core-shell-type modified SBR as
second binder 16, 10 parts by weight; and - distilled water, 200 parts by weight.
The mixing ratio offirst binder 15 is 13.3 parts by weight with respect to 100 parts by weight of SiO. The mixing ratio ofsecond binder 16 is 40 parts by weight with respect to 100 parts by weight ofCNFs 12.
- composite negative electrode
- The resulting negative electrode mixture slurry is applied to a 14 μM thick copper (Cu) foil as
current collector 1A and dried in a manner that the electrode plate thickness after drying becomes 100 μm. The plate is stamped into a square having sides of 11 mm to obtainnegative electrode 1. - A flat model cell is formed of
negative electrode 1 thus produced, a square metallic lithium foil having a thickness of 300 μm and sides of 13 mm ascounter electrode 2, and a polyethylene microporous film having a thickness of 20 μm and a porosity of about 40% asseparator 3. The model cell is inserted intolaminate bag 4. Afteraqueous electrolyte 5 is injected into it,laminate bag 4 is sealed.Aqueous electrolyte 5 is a solution dissolving LiPF6 at a concentration of 1 mol/dm3 in a mixture solvent of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) (volume ratio EC: DMC: EMC=2:3:3). The designed capacity (C, in mAh) of the obtained model cell ofsample 1 is 5 mAh. - The model cells of
samples 2 to 7 are produced similarly tosample 1, except that mixing ratios of polyacrylic acid that is used asfirst binder 15 insample 1, with respect to 100 parts by weight of composite negative electrodeactive material 14, are set at 0.4, 0.7, 3.8, 15, 22.5, and 28 parts by weight, respectively, in producing each composite negative electrodeactive material 14 and eachnegative electrode 1 forsamples 2 to 7. Insamples 2 to 7, mixing ratios offirst binder 15 with respect to 100 parts by weight of SiO are 0.5, 1, 5, 20, 30, and 37.3 parts by weight, respectively. - The model cells of samples 8 to 13 are produced similarly to
sample 1, except that mixing ratios of BM-400B that is used asbinder 16 insample 1, with respect to 100 parts by weight of composite negative electrodeactive material 14, are set at 0.4, 0.8, 2.5, 15, 20, and 24 parts by weight, respectively, in producing each composite negative electrodeactive material 14 and eachnegative electrode 1 for samples 8 to 13. In samples 8 to 13, mixing ratios ofsecond binder 16 are 3, 10, 60, 80, and 96 parts by weight, respectively, with respect to 100 parts by weight ofCNFs 12. - In producing
sample 14,CNFs 12 are grown on the surfaces of SiO particles similarly tosample 1 except that the reaction time is set at 80 minutes. Extending the reaction time increases the content ofCNFs 12 to 30 parts by weight with respect to 100 parts by weight of SiO. The model cell ofsample 14 is produced similarly tosample 1, except that 9.5 parts by weight of polyacrylic acid asfirst binder 15 and 9.5 parts by weight of BM-400B assecond binder 16 are added with respect to 100 parts by weight of composite negative electrodeactive material 14. The mixing ratio offirst binder 15 is 13.6 parts by weight with respect to 100 parts by weight of SiO. The mixing ratio ofsecond binder 16 is 31.7 parts by weight with respect to 100 parts by weight ofCNFs 12. - The model cell of
sample 15 is produced similarly tosample 1 except that copper foil ascurrent collector 1A is sandblasted and the surface thereof is roughened so that surface roughness Ra is increased from 0.1 μm to 1 μm. - In
sample 16, two kinds of negative electrode mixture slurries are used. First slurry ofsample 16 is prepared similarly to the negative electrode mixture slurry ofsample 1 except that the mixing ratio of polyacrylic acid asfirst binder 15 is set at 0.7 parts by weight with respect to 100 parts by weight of obtained composite negative electrodeactive material 14. The mixing ratio offirst binder 15 is 1 part by weight with respect to 100 parts by weight of SiO. While, second slurry ofsample 16 is prepared similarly to the negative electrode mixture slurry ofsample 1 except that the mixing ratio of polyacrylic acid is set at 22.4 parts by weight with respect to 100 parts by weight of composite negative electrodeactive material 14. The mixing ratio offirst binder 15 is 30 parts by weight with respect to 100 parts by weight of SiO. The second slurry is firstly applied to copper foil ascurrent collector 1A so that the thickness after drying is 43 μm to form a lower layer, and the first slurry is then applied to the second slurry so that the thickness after drying is 43 μm to form an upper layer. Except for this condition, the model cell ofsample 16 is produced similarly tosample 1. - In sample 17, before
mixture layer 1B is formed, bindinglayer 20 is formed oncurrent collector 1A. In formingbinding layer current collector 1A so that the thickness after drying is 5 μm, and the same slurry as the negative electrode mixture slurry used forsample 1 is then applied and dried, thereby formingbinding layer 20. In this way, except thatbinding layer 20 is formed, the model cell of sample 17 is produced similarly tosample 1. - Initial charge capacity and initial discharge capacity of each model cell of
samples 1 to 17 thus produced are measured at a charge-discharge current of 0.1 CmA. The discharge capacity thus measured is converted into a value per unit volume (1 cm3) ofmixture layer 1B to obtain and discharge capacity density is calculated. The cell is charged until the voltage across the electrodes reaches 0 V, and the cell is discharged until the voltage reaches 1.5 V. Here, 0.1 CmA indicates a current value obtained by dividing the designed capacity of batteries by 10 hours. - The high-load characteristics of each model cell of
samples 1 to 17 are then evaluated. Each model cell is charged at a current of 0.1 CmA, and then discharged at a current of 0.5 CmA so as to obtain the discharge capacity at 0.5 CmA. The discharge capacity thus obtained is divided by the discharge capacity at 0.1 CmA to estimate the capacity retention rate, which is used as an index of the high-load characteristics. - Finally, the charge-discharge cycle characteristics are evaluated. Charge and discharge are repeated under the same conditions as the initial capacity measurement. The rest time between each charge and discharge is set at 20 minutes. In the discharge state after five cycles, each model cell of
samples 1 to 17 is disassembled, andmixture layer 1B is observed to see whether peeling or separation occurs. The charge-discharge cycle is repeated for each model cell. The cycle number until the discharge capacity reaches 60% of the initial discharge capacity is used as an index of the cycle characteristics of each model cell. - By referring to the case where a negative electrode using graphite as the active material is used, the evaluation standard of the capacity retention rate is set at 60% or more. The evaluation standard of the cycle number is set at 50 cycles or more in consideration of practicality. Table 1 shows the composition of each negative electrode of
samples 1 to 17 and evaluation results of the characteristics of each model cell. -
TABLE 1 Added second Added first binders High-load SiO CNF binders (parts by capacity weight weight (parts by weight to Cycle retention proportions proportions weight to SiO) CNF) Others numbers rates (%) Sample 1100 25 13.3 40 65 82 Sample 2100 25 0.5 40 8 61 Sample 3100 25 1 40 52 86 Sample 4100 25 5 40 57 85 Sample 5100 25 20 40 61 84 Sample 6 100 25 30 40 57 81 Sample 7100 25 37.3 40 53 70 Sample 8 100 25 13.3 1.6 16 64 Sample 9 100 25 13.3 3 54 81 Sample 10 100 25 1.3 10 55 91 Sample 11100 25 13.3 60 59 92 Sample 12100 25 13.3 80 56 83 Sample 13100 25 13.3 96 54 58 Sample 14100 30 13.3 40 53 82 Sample 15100 25 13.3 40 Current 61 84 collector with rough surface Sample 16 100 25 Lower layer: 30 Both 64 81 Upper layer: 1 lower and upper layers: 40 Sample 17 100 25 13.3 40 Existence 60 83 of binding layer - As is clear from Table 1, the model cells of
samples 1 to 17 using negative electrodes that containfirst binder 15 composed of an acryl-group-containing polymer andsecond binder 16 composed of adhesive rubber particles have sufficient high-load discharge characteristics and sufficient cycle characteristics. Most of all, the model cells ofsample 1,samples 3 to 6, samples 9 to 12, andsamples samples first binder 15 is 5 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of SiO, and the content ofsecond binder 16 is 10 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight ofCNFs 12. - In
sample 15 havingcurrent collector 1A with a roughened surface,current collector 1A has an increased area for the adsorption offirst binder 15 having a high affinity tocurrent collector 1A, and hence the binding property is further increased and the cycle characteristics are further improved. - In
sample 16, the content offirst binder 15 having a high affinity tocurrent collector 1A is set higher nearcurrent collector 1A, so that peeling ofmixture layer 1B fromcurrent collector 1A caused by rapid expansion and contraction of SiO is significantly reduced and cycle characteristics are further improved. - In sample 17, binding
layer 20 containingfirst binder 15 is disposed oncurrent collector 1A, andmixture layer 1B is stuck tocurrent collector 1A. Therefore, cycle characteristics are further improved similarly to sample 16. - In
sample 14, composition ofCNFs 12 and SiO of silicon-containingparticles 11 in composite negative electrodeactive material 14 is changed. In this case, by making adequate the mixing ratio offirst binder 15 to SiO and the mixing ratio ofsecond binder 16 to CNFs 12, a negative electrode for non-aqueous electrolyte secondary batteries having excellent cycle characteristics and excellent high-load discharge characteristics is also obtained. - In
sample 2 where the content offirst binder 15 is less than 1 part by weight with respect to 100 parts by weight of SiO, the cycle characteristics are low. This is probably because repetition of charge and discharge (expansion and contraction) makes loose the binding betweenmixture layer 1B andcurrent collector 1A and makesmixture layer 1B easy to peel off. When the model cell is disassembled and inspected after evaluating the characteristics thereof, peeling is actually observed. Insample 7 where the content offirst binder 15 exceeds 30 part by weight with respect to 100 parts by weight of SiO, the high-load discharge characteristics are low. That is probably because excessively covering silicon-containingparticles 11 withfirst binder 15 reduces the ion conductivity. - In sample 8 where the content of
second binder 16 is less than 3 parts by weight with respect to 100 parts by weight ofCNFs 12, the cycle characteristics are also low. This is probably because repetition of charge and discharge (expansion and contraction) makes loose the binding inmixture layer 1B and makes composite negative electrodeactive material 14 easy to peel off. When the model cell is disassembled and inspected after evaluating the characteristics thereof, peeling is actually observed. Insample 13 where the content ofsecond binder 16 exceeds 80 part by weight with respect to 100 parts by weight ofCNFs 12, the high-load discharge characteristics are also low. This is probably because excessively coveringCNFs 12 withsecond binder 16 reduces the electrical conductivity. - The advantages of the present invention have been described with reference to specific experiments using the model cells having a structure of
FIG. 1 and their results. However, when a positive electrode capable of charging and discharging lithium ions is used instead of metallic lithium used ascounter electrode 2, a laminate type non-aqueous electrolyte secondary battery sealed inlaminate bag 4 can be obtained. The positive electrode has a mixture layer containing, as a positive electrode active material, a lithium-containing compound such as LiCoO2, LiNiO2, Li2MnO4, a mixture of them, or a composite oxide of them. Such a positive electrode active material reduces lithium ions at least during discharge, and contains lithium ions in an uncharged state. In a structure wherenegative electrode 1 does not contain lithium in an uncharged state, the positive electrode needs to contain lithium ions as in the present case. Whennegative electrode 1 having the structure as described above is used in a non-aqueous electrolyte secondary battery having this structure, a battery having sufficient high-load characteristics and sufficient cycle characteristics is achieved. - Specific examples of the positive electrode active material include, in addition to the lithium-containing composite oxides mentioned above, lithium-containing compounds such as olivine-type lithium phosphate expressed by a general formula: LiMPO4, where M=V, Fe, Ni, or Mn, and lithium fluorophosphate expressed by a general formula: Li2 MPO4F, where M=V, Fe, Ni, or Mn. It is also possible to replace part of the constituent elements of these lithium-containing compounds by a different element. The surfaces of these lithium-containing compounds may be treated with metal oxide, lithium oxide, a conductive agent or the like, or may be subjected to hydrophobic treatment.
- Specific examples of the conductive agent to be used for the positive electrode include the following materials: graphites such as natural graphite and artificial graphite; carbon blacks such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; metal powders such as aluminum powder; conductive whiskers such as zinc oxide whisker and potassium titanate whisker; conductive metal oxides such as titanium oxide; and organic conductive materials such as a phenylene derivative.
- Specific examples of the binder for the positive electrode include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethylacrylate ester, polyethylacrylate ester, polyhexylacrylate ester, polymethacrylic acid, polymethyl methacrylate ester, polyethylmethacrylate ester, polyhexyl methacrylate ester, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, and carboxymethyl cellulose. Further other examples of the binder include copolymers containing at least two selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkylvinylether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethylvinylether, acrylic acid, and hexadiene. Alternatively, two or more of these copolymers can be mixed.
- The current collector and the lead used for the positive electrode can be made of stainless steel, aluminum, titanium, carbon, conductive resin, or the like. These materials may be surface-treated with carbon, nickel, titanium or the like.
- The structure of the battery is not limited to the aforementioned laminate-type battery structure in which rectangular positive and negative electrode plates face each other. A coin-shaped battery structure where circular positive and negative electrode plates face each other, a cylindrical battery structure where thin and long positive and negative electrodes are wound, or a prismatic battery structure can be used. Any of these structures provides the same advantages as the laminate-type battery structure. Coin-shaped batteries do not always need
current collector 1A, andmixture layer 1B may be formed directly on the inner surface of a metal case which is made of iron, nickel-plated iron, or the like and also serves as an external terminal. Furthermore, instead of using a wet process of handling negative electrode mixture slurry, the composite negative electrode active material may be mixed with a powdered binder and then pressed. - A negative electrode for non-aqueous electrolyte secondary batteries related to the present invention can provide a high-capacity non-aqueous electrolyte secondary battery having improved high-load discharge characteristics and cycle characteristics. The negative electrode contributes to the increase in energy density of lithium batteries expected to have growing demand.
Claims (6)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2005358754A JP5162825B2 (en) | 2005-12-13 | 2005-12-13 | Negative electrode for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery using the same |
JP2005-358754 | 2005-12-13 | ||
PCT/JP2006/320824 WO2007069389A1 (en) | 2005-12-13 | 2006-10-19 | Negative electrode for nonaqueous electrolyte secondary battery and, making use of the same, nonaqueous electrolyte secondary battery |
Publications (2)
Publication Number | Publication Date |
---|---|
US20090004566A1 true US20090004566A1 (en) | 2009-01-01 |
US7892677B2 US7892677B2 (en) | 2011-02-22 |
Family
ID=38162704
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/664,805 Expired - Fee Related US7892677B2 (en) | 2005-12-13 | 2006-10-19 | Negative electrode for non-aqueous electrolyte secondary batteries, and non-aqueous electrolyte secondary battery having the same |
Country Status (5)
Country | Link |
---|---|
US (1) | US7892677B2 (en) |
JP (1) | JP5162825B2 (en) |
KR (1) | KR100832205B1 (en) |
CN (1) | CN100495769C (en) |
WO (1) | WO2007069389A1 (en) |
Cited By (58)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080318126A1 (en) * | 2007-06-21 | 2008-12-25 | Sony Corporation | Cathode mix and nonaqueous electrolyte battery |
US20090023065A1 (en) * | 2007-07-19 | 2009-01-22 | Samsung Sdi Co., Ltd. | Composite anode active material, anode including the same and lithium battery using the anode |
US20100258761A1 (en) * | 2005-10-17 | 2010-10-14 | Gue-Sung Kim | Anode active material, method of preparing the same, and anode and lithium battery containing the material |
US20100330421A1 (en) * | 2009-05-07 | 2010-12-30 | Yi Cui | Core-shell high capacity nanowires for battery electrodes |
US20110014521A1 (en) * | 2008-03-10 | 2011-01-20 | Nissan Motor Co., Ltd. | Battery with battery electrode and method of manufacturing same |
US20110020701A1 (en) * | 2009-07-16 | 2011-01-27 | Carbon Micro Battery Corporation | Carbon electrode structures for batteries |
US20110111304A1 (en) * | 2009-11-11 | 2011-05-12 | Amprius, Inc. | Preloading lithium ion cell components with lithium |
US20110165465A1 (en) * | 2010-01-07 | 2011-07-07 | Samsung Sdi Co., Ltd. | Negative active material for rechargeable lithium battery, method of preparing same, and rechargeable lithium battery including same |
US20110171502A1 (en) * | 2010-01-11 | 2011-07-14 | Amprius, Inc. | Variable capacity cell assembly |
US20110177393A1 (en) * | 2010-01-18 | 2011-07-21 | Enevate Corporation | Composite materials for electrochemical storage |
WO2012175998A1 (en) * | 2011-06-24 | 2012-12-27 | Nexeon Limited | Structured particles |
US20130122353A1 (en) * | 2010-09-02 | 2013-05-16 | Nec Corporation | Secondary battery |
US20140146439A1 (en) * | 2012-11-27 | 2014-05-29 | Samsung Electro-Mechanics Co., Ltd. | Electrode structure and method for manufacturing the same, and energy storage device including the electrode structure |
US20140170490A1 (en) * | 2012-06-13 | 2014-06-19 | City Of Nagoya | Lithium secondary battery negative electrode and method for manufacturing the same |
US20140220411A1 (en) * | 2010-02-25 | 2014-08-07 | Lg Chem, Ltd. | Separator for electrochemical device and electrochemical device including the separator |
US20150056510A1 (en) * | 2013-08-20 | 2015-02-26 | Samsung Sdi Co., Ltd. | Negative active material for rechargeable lithium battery, method of preparing same, and negative electrode and rechargeable lithium battery including same |
US9048492B2 (en) | 2011-05-25 | 2015-06-02 | Nissan Motor Co., Ltd. | Negative electrode active material for electric device |
US9142864B2 (en) | 2010-11-15 | 2015-09-22 | Amprius, Inc. | Electrolytes for rechargeable batteries |
US9231243B2 (en) | 2009-05-27 | 2016-01-05 | Amprius, Inc. | Interconnected hollow nanostructures containing high capacity active materials for use in rechargeable batteries |
US9349544B2 (en) | 2009-02-25 | 2016-05-24 | Ronald A Rojeski | Hybrid energy storage devices including support filaments |
US9362549B2 (en) | 2011-12-21 | 2016-06-07 | Cpt Ip Holdings, Llc | Lithium-ion battery anode including core-shell heterostructure of silicon coated vertically aligned carbon nanofibers |
US9397338B2 (en) | 2010-12-22 | 2016-07-19 | Enevate Corporation | Electrodes, electrochemical cells, and methods of forming electrodes and electrochemical cells |
US9412998B2 (en) | 2009-02-25 | 2016-08-09 | Ronald A. Rojeski | Energy storage devices |
US9431181B2 (en) | 2009-02-25 | 2016-08-30 | Catalyst Power Technologies | Energy storage devices including silicon and graphite |
US9548489B2 (en) | 2012-01-30 | 2017-01-17 | Nexeon Ltd. | Composition of SI/C electro active material |
US9553303B2 (en) | 2010-01-18 | 2017-01-24 | Enevate Corporation | Silicon particles for battery electrodes |
US9583757B2 (en) | 2010-12-22 | 2017-02-28 | Enevate Corporation | Electrodes, electrochemical cells, and methods of forming electrodes and electrochemical cells |
US9705136B2 (en) | 2008-02-25 | 2017-07-11 | Traverse Technologies Corp. | High capacity energy storage |
US9917300B2 (en) | 2009-02-25 | 2018-03-13 | Cf Traverse Llc | Hybrid energy storage devices including surface effect dominant sites |
US9923201B2 (en) | 2014-05-12 | 2018-03-20 | Amprius, Inc. | Structurally controlled deposition of silicon onto nanowires |
US9941709B2 (en) | 2009-02-25 | 2018-04-10 | Cf Traverse Llc | Hybrid energy storage device charging |
US9966197B2 (en) | 2009-02-25 | 2018-05-08 | Cf Traverse Llc | Energy storage devices including support filaments |
US9979017B2 (en) | 2009-02-25 | 2018-05-22 | Cf Traverse Llc | Energy storage devices |
US20180159135A1 (en) * | 2015-05-08 | 2018-06-07 | Toppan Printing Co., Ltd. | Electrode for nonaqueous electrolyte secondary cell and nonaqueous electrolyte secondary cell |
US10008716B2 (en) | 2012-11-02 | 2018-06-26 | Nexeon Limited | Device and method of forming a device |
US10056602B2 (en) | 2009-02-25 | 2018-08-21 | Cf Traverse Llc | Hybrid energy storage device production |
US10090513B2 (en) | 2012-06-01 | 2018-10-02 | Nexeon Limited | Method of forming silicon |
US10090512B2 (en) | 2009-05-07 | 2018-10-02 | Amprius, Inc. | Electrode including nanostructures for rechargeable cells |
US10103379B2 (en) | 2012-02-28 | 2018-10-16 | Nexeon Limited | Structured silicon particles |
US10193142B2 (en) | 2008-02-25 | 2019-01-29 | Cf Traverse Llc | Lithium-ion battery anode including preloaded lithium |
US10388943B2 (en) | 2010-12-22 | 2019-08-20 | Enevate Corporation | Methods of reducing occurrences of short circuits and/or lithium plating in batteries |
US10396355B2 (en) | 2014-04-09 | 2019-08-27 | Nexeon Ltd. | Negative electrode active material for secondary battery and method for manufacturing same |
US10461366B1 (en) | 2010-01-18 | 2019-10-29 | Enevate Corporation | Electrolyte compositions for batteries |
US10476072B2 (en) | 2014-12-12 | 2019-11-12 | Nexeon Limited | Electrodes for metal-ion batteries |
US10541412B2 (en) | 2015-08-07 | 2020-01-21 | Enevate Corporation | Surface modification of silicon particles for electrochemical storage |
US10586976B2 (en) | 2014-04-22 | 2020-03-10 | Nexeon Ltd | Negative electrode active material and lithium secondary battery comprising same |
US10665858B2 (en) | 2009-02-25 | 2020-05-26 | Cf Traverse Llc | Energy storage devices |
US10686214B2 (en) | 2017-12-07 | 2020-06-16 | Enevate Corporation | Sandwich electrodes and methods of making the same |
US10707478B2 (en) | 2017-12-07 | 2020-07-07 | Enevate Corporation | Silicon particles for battery electrodes |
US11075378B2 (en) | 2008-02-25 | 2021-07-27 | Cf Traverse Llc | Energy storage devices including stabilized silicon |
US11133498B2 (en) | 2017-12-07 | 2021-09-28 | Enevate Corporation | Binding agents for electrochemically active materials and methods of forming the same |
US11233234B2 (en) | 2008-02-25 | 2022-01-25 | Cf Traverse Llc | Energy storage devices |
US11380890B2 (en) | 2010-01-18 | 2022-07-05 | Enevate Corporation | Surface modification of silicon particles for electrochemical storage |
US11387443B1 (en) | 2021-11-22 | 2022-07-12 | Enevate Corporation | Silicon based lithium ion battery and improved cycle life of same |
US20220302520A1 (en) * | 2021-03-16 | 2022-09-22 | Beam Global | Phase change composite apparatus for battery packs and methods of making |
IT202100017024A1 (en) * | 2021-06-29 | 2022-12-29 | Pierfrancesco Atanasio | Carbon/active material hybrid electrodes for lithium ion batteries |
WO2023044579A1 (en) * | 2021-09-24 | 2023-03-30 | Rangom Yverick Pascal | Electrodes comprising covalently joined carbonaceous and metalloid powders and methods of manufacturing same |
US11891523B2 (en) | 2019-09-30 | 2024-02-06 | Lg Energy Solution, Ltd. | Composite negative electrode active material, method of manufacturing the same, and negative electrode including the same |
Families Citing this family (21)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA2897320A1 (en) | 2005-07-28 | 2007-01-28 | Nanocomp Technologies, Inc. | Systems and methods for formation and harvesting of nanofibrous materials |
US7875388B2 (en) | 2007-02-06 | 2011-01-25 | 3M Innovative Properties Company | Electrodes including polyacrylate binders and methods of making and using the same |
AU2008283846A1 (en) | 2007-08-07 | 2009-02-12 | Nanocomp Technologies, Inc. | Electrically and thermally non-metallic conductive nanostructure-based adapters |
KR101307623B1 (en) * | 2008-02-25 | 2013-09-12 | 로날드 앤쏘니 로제스키 | High capacity electrodes |
JP5605533B2 (en) * | 2008-12-25 | 2014-10-15 | 日本ゼオン株式会社 | Electrode composition layer with support and method for producing electrode for electrochemical device |
WO2012029373A1 (en) * | 2010-08-31 | 2012-03-08 | トヨタ自動車株式会社 | Negative electrode material, lithium secondary battery, and method for producing negative electrode material |
JP6003015B2 (en) | 2011-06-24 | 2016-10-05 | ソニー株式会社 | Lithium ion secondary battery, negative electrode for lithium ion secondary battery, battery pack, electric vehicle, power storage system, electric tool and electronic device |
WO2013158174A1 (en) * | 2012-02-07 | 2013-10-24 | Nanocomp Technologies, Inc. | Nanostructure composite batteries and methods of making same from nanostructure composite sheets |
JP5754855B2 (en) * | 2012-04-25 | 2015-07-29 | 信越化学工業株式会社 | Anode for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery |
WO2014031440A1 (en) * | 2012-08-23 | 2014-02-27 | Nanocomp Technologies, Inc. | Batteries having nanostructured composite cathode |
WO2014204561A1 (en) | 2013-06-17 | 2014-12-24 | Nanocomp Technologies, Inc. | Exfoliating-dispersing agents for nanotubes, bundles and fibers |
CN103413922B (en) * | 2013-08-14 | 2016-08-17 | 湖北万润新能源科技发展有限公司 | The preparation method of lithium ion battery negative material |
KR101631847B1 (en) * | 2014-03-25 | 2016-06-27 | 전자부품연구원 | Anode slurry for lithium-ion battery, and method for fabricating thereof |
JP6821575B2 (en) | 2015-02-03 | 2021-01-27 | ナノコンプ テクノロジーズ,インク. | Carbon Nanotube Structures and Methods for Their Formation |
CN106159246B (en) * | 2015-03-31 | 2019-12-06 | 中国科学院金属研究所 | Silicon-containing porous amorphous alloy lithium ion battery negative electrode material and preparation method thereof |
KR20170055325A (en) | 2015-11-11 | 2017-05-19 | 현대자동차주식회사 | Electrolyte layer for all-solid state battery and method of manufacturing the all-solid state battery using the same |
CN107346831A (en) * | 2016-05-04 | 2017-11-14 | 上海奇谋能源技术开发有限公司 | A kind of method for improving lithium ion battery service life |
US10581082B2 (en) | 2016-11-15 | 2020-03-03 | Nanocomp Technologies, Inc. | Systems and methods for making structures defined by CNT pulp networks |
US11387442B2 (en) | 2017-08-24 | 2022-07-12 | Nec Corporation | Negative electrode for lithium ion secondary battery and lithium ion secondary battery comprising the same |
JP6876648B2 (en) * | 2018-03-22 | 2021-05-26 | 株式会社東芝 | Rechargeable batteries, battery packs and vehicles |
JP7262492B2 (en) * | 2021-01-13 | 2023-04-21 | プライムプラネットエナジー&ソリューションズ株式会社 | Negative electrode active material, lithium ion battery, and method for producing negative electrode active material |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5571638A (en) * | 1993-09-30 | 1996-11-05 | Sumitomo Chemical Company Limited | Lithium secondary battery |
US5783331A (en) * | 1995-08-01 | 1998-07-21 | Ricoh Company, Ltd. | Second battery comprising a gel polymer solid electrolyte and a copolymer of vinyl pyridine with a hydroxyl-group-containing (meth) acrylate as binder for the negative electrode |
US20020061440A1 (en) * | 2000-09-04 | 2002-05-23 | Matsushita Electric Industrial Co., Ltd. | Non-aqueous electrolyte secondary battery and negative electrode for the same |
US6440610B1 (en) * | 1999-12-10 | 2002-08-27 | Samsung Sdi Co., Ltd. | Negative active material for lithium secondary battery and manufacturing method of same |
US20030054243A1 (en) * | 2001-09-14 | 2003-03-20 | Matsushita Electric Industrial Co., Ltd. | Non-aqueous electrolyte secondary battery and production method thereof |
US20030087152A1 (en) * | 2001-11-08 | 2003-05-08 | Tadafumi Shindo | Coating composition for negative electrode, negative electrode plate, method for producing the same, and secondary battery with nonaqueous electrolyte |
US20060115730A1 (en) * | 2004-11-30 | 2006-06-01 | Matsushita Electric Industrial Co., Ltd. | Non-aqueous electrolyte secondary battery |
US20070092796A1 (en) * | 2005-06-06 | 2007-04-26 | Hiroaki Matsuda | Non-aqueous electrolyte secondary battery |
US20070111102A1 (en) * | 2005-11-14 | 2007-05-17 | Kaoru Inoue | Negative electrode for non-aqueous electrolyte secondary batteries, non-aqueous electrolyte secondary battery having the electrode, and method for producing negative electrode for non-aqueous electrolyte secondary batteries |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4441935B2 (en) | 1998-06-09 | 2010-03-31 | パナソニック株式会社 | Negative electrode for non-aqueous electrolyte secondary battery and battery using the same |
JP4212263B2 (en) * | 2000-09-01 | 2009-01-21 | 三洋電機株式会社 | Negative electrode for lithium secondary battery and method for producing the same |
JP2004214046A (en) * | 2003-01-06 | 2004-07-29 | Matsushita Electric Ind Co Ltd | Electrode for lithium-ion secondary battery and lithium-ion secondary battery using the same |
JP2004349056A (en) | 2003-05-21 | 2004-12-09 | Mitsui Mining Co Ltd | Anode material for lithium secondary battery and its manufacturing method |
JP4815817B2 (en) * | 2004-02-16 | 2011-11-16 | 東レ株式会社 | Method for producing carbon nanotube |
JP2005272261A (en) * | 2004-03-26 | 2005-10-06 | Toray Ind Inc | Method for producing carbon nanotube |
-
2005
- 2005-12-13 JP JP2005358754A patent/JP5162825B2/en not_active Expired - Fee Related
-
2006
- 2006-10-19 CN CNB2006800011211A patent/CN100495769C/en not_active Expired - Fee Related
- 2006-10-19 US US11/664,805 patent/US7892677B2/en not_active Expired - Fee Related
- 2006-10-19 KR KR1020077006236A patent/KR100832205B1/en not_active IP Right Cessation
- 2006-10-19 WO PCT/JP2006/320824 patent/WO2007069389A1/en active Application Filing
Patent Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5571638A (en) * | 1993-09-30 | 1996-11-05 | Sumitomo Chemical Company Limited | Lithium secondary battery |
US5783331A (en) * | 1995-08-01 | 1998-07-21 | Ricoh Company, Ltd. | Second battery comprising a gel polymer solid electrolyte and a copolymer of vinyl pyridine with a hydroxyl-group-containing (meth) acrylate as binder for the negative electrode |
US6440610B1 (en) * | 1999-12-10 | 2002-08-27 | Samsung Sdi Co., Ltd. | Negative active material for lithium secondary battery and manufacturing method of same |
US20020061440A1 (en) * | 2000-09-04 | 2002-05-23 | Matsushita Electric Industrial Co., Ltd. | Non-aqueous electrolyte secondary battery and negative electrode for the same |
US6773838B2 (en) * | 2000-09-04 | 2004-08-10 | Matsushita Electric Industrial Co., Ltd. | Non-aqueous electrolyte secondary battery and negative electrode for the same |
US20030054243A1 (en) * | 2001-09-14 | 2003-03-20 | Matsushita Electric Industrial Co., Ltd. | Non-aqueous electrolyte secondary battery and production method thereof |
US20030087152A1 (en) * | 2001-11-08 | 2003-05-08 | Tadafumi Shindo | Coating composition for negative electrode, negative electrode plate, method for producing the same, and secondary battery with nonaqueous electrolyte |
US20060115730A1 (en) * | 2004-11-30 | 2006-06-01 | Matsushita Electric Industrial Co., Ltd. | Non-aqueous electrolyte secondary battery |
US20070092796A1 (en) * | 2005-06-06 | 2007-04-26 | Hiroaki Matsuda | Non-aqueous electrolyte secondary battery |
US20070111102A1 (en) * | 2005-11-14 | 2007-05-17 | Kaoru Inoue | Negative electrode for non-aqueous electrolyte secondary batteries, non-aqueous electrolyte secondary battery having the electrode, and method for producing negative electrode for non-aqueous electrolyte secondary batteries |
Cited By (118)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8628884B2 (en) | 2005-10-17 | 2014-01-14 | Samsung Sdi Co., Ltd. | Anode active material, method of preparing the same, and anode and lithium battery containing the material |
US20100258761A1 (en) * | 2005-10-17 | 2010-10-14 | Gue-Sung Kim | Anode active material, method of preparing the same, and anode and lithium battery containing the material |
US9893357B2 (en) * | 2007-06-21 | 2018-02-13 | Murata Manufacturing Co., Ltd. | Cathode mix and nonaqueous electrolyte battery |
US20080318126A1 (en) * | 2007-06-21 | 2008-12-25 | Sony Corporation | Cathode mix and nonaqueous electrolyte battery |
US20090023065A1 (en) * | 2007-07-19 | 2009-01-22 | Samsung Sdi Co., Ltd. | Composite anode active material, anode including the same and lithium battery using the anode |
US8906554B2 (en) | 2007-07-19 | 2014-12-09 | Samsung Sdi Co., Ltd. | Composite anode active material, anode including the same and lithium battery using the anode |
US11233234B2 (en) | 2008-02-25 | 2022-01-25 | Cf Traverse Llc | Energy storage devices |
US10193142B2 (en) | 2008-02-25 | 2019-01-29 | Cf Traverse Llc | Lithium-ion battery anode including preloaded lithium |
US9705136B2 (en) | 2008-02-25 | 2017-07-11 | Traverse Technologies Corp. | High capacity energy storage |
US11152612B2 (en) | 2008-02-25 | 2021-10-19 | Cf Traverse Llc | Energy storage devices |
US11127948B2 (en) | 2008-02-25 | 2021-09-21 | Cf Traverse Llc | Energy storage devices |
US11075378B2 (en) | 2008-02-25 | 2021-07-27 | Cf Traverse Llc | Energy storage devices including stabilized silicon |
US10978702B2 (en) | 2008-02-25 | 2021-04-13 | Cf Traverse Llc | Energy storage devices |
US11502292B2 (en) | 2008-02-25 | 2022-11-15 | Cf Traverse Llc | Lithium-ion battery anode including preloaded lithium |
US10964938B2 (en) | 2008-02-25 | 2021-03-30 | Cf Traverse Llc | Lithium-ion battery anode including preloaded lithium |
EP2250689A4 (en) * | 2008-03-10 | 2012-09-19 | Nissan Motor | Battery with battery electrode and method of manufacturing same |
US9105939B2 (en) | 2008-03-10 | 2015-08-11 | Nissan Motor Co., Ltd. | Battery with battery electrode and method of manufacturing same |
US20110014521A1 (en) * | 2008-03-10 | 2011-01-20 | Nissan Motor Co., Ltd. | Battery with battery electrode and method of manufacturing same |
US10741825B2 (en) | 2009-02-25 | 2020-08-11 | Cf Traverse Llc | Hybrid energy storage device production |
US10727482B2 (en) | 2009-02-25 | 2020-07-28 | Cf Traverse Llc | Energy storage devices |
US10665858B2 (en) | 2009-02-25 | 2020-05-26 | Cf Traverse Llc | Energy storage devices |
US9941709B2 (en) | 2009-02-25 | 2018-04-10 | Cf Traverse Llc | Hybrid energy storage device charging |
US10714267B2 (en) | 2009-02-25 | 2020-07-14 | Cf Traverse Llc | Energy storage devices including support filaments |
US10673250B2 (en) | 2009-02-25 | 2020-06-02 | Cf Traverse Llc | Hybrid energy storage device charging |
US10622622B2 (en) | 2009-02-25 | 2020-04-14 | Cf Traverse Llc | Hybrid energy storage devices including surface effect dominant sites |
US10461324B2 (en) | 2009-02-25 | 2019-10-29 | Cf Traverse Llc | Energy storage devices |
US9966197B2 (en) | 2009-02-25 | 2018-05-08 | Cf Traverse Llc | Energy storage devices including support filaments |
US9979017B2 (en) | 2009-02-25 | 2018-05-22 | Cf Traverse Llc | Energy storage devices |
US9349544B2 (en) | 2009-02-25 | 2016-05-24 | Ronald A Rojeski | Hybrid energy storage devices including support filaments |
US10727481B2 (en) | 2009-02-25 | 2020-07-28 | Cf Traverse Llc | Energy storage devices |
US9917300B2 (en) | 2009-02-25 | 2018-03-13 | Cf Traverse Llc | Hybrid energy storage devices including surface effect dominant sites |
US10056602B2 (en) | 2009-02-25 | 2018-08-21 | Cf Traverse Llc | Hybrid energy storage device production |
US9412998B2 (en) | 2009-02-25 | 2016-08-09 | Ronald A. Rojeski | Energy storage devices |
US9431181B2 (en) | 2009-02-25 | 2016-08-30 | Catalyst Power Technologies | Energy storage devices including silicon and graphite |
US10090512B2 (en) | 2009-05-07 | 2018-10-02 | Amprius, Inc. | Electrode including nanostructures for rechargeable cells |
US10811675B2 (en) | 2009-05-07 | 2020-10-20 | Amprius, Inc. | Electrode including nanostructures for rechargeable cells |
US20100330421A1 (en) * | 2009-05-07 | 2010-12-30 | Yi Cui | Core-shell high capacity nanowires for battery electrodes |
US10461359B2 (en) | 2009-05-27 | 2019-10-29 | Amprius, Inc. | Interconnected hollow nanostructures containing high capacity active materials for use in rechargeable batteries |
US9231243B2 (en) | 2009-05-27 | 2016-01-05 | Amprius, Inc. | Interconnected hollow nanostructures containing high capacity active materials for use in rechargeable batteries |
US20110020701A1 (en) * | 2009-07-16 | 2011-01-27 | Carbon Micro Battery Corporation | Carbon electrode structures for batteries |
US11769870B2 (en) | 2009-07-16 | 2023-09-26 | Enevate Corporation | Carbon electrode structures for batteries |
US8846251B2 (en) * | 2009-11-11 | 2014-09-30 | Amprius, Inc. | Preloading lithium ion cell components with lithium |
US20150004495A1 (en) * | 2009-11-11 | 2015-01-01 | Amprius, Inc. | Preloading lithium ion cell components with lithium |
US20110111304A1 (en) * | 2009-11-11 | 2011-05-12 | Amprius, Inc. | Preloading lithium ion cell components with lithium |
US20110165465A1 (en) * | 2010-01-07 | 2011-07-07 | Samsung Sdi Co., Ltd. | Negative active material for rechargeable lithium battery, method of preparing same, and rechargeable lithium battery including same |
US20110171502A1 (en) * | 2010-01-11 | 2011-07-14 | Amprius, Inc. | Variable capacity cell assembly |
US10461366B1 (en) | 2010-01-18 | 2019-10-29 | Enevate Corporation | Electrolyte compositions for batteries |
US11728476B2 (en) | 2010-01-18 | 2023-08-15 | Enevate Corporation | Surface modification of silicon particles for electrochemical storage |
US9553303B2 (en) | 2010-01-18 | 2017-01-24 | Enevate Corporation | Silicon particles for battery electrodes |
US10622620B2 (en) | 2010-01-18 | 2020-04-14 | Enevate Corporation | Methods of forming composite material films |
US11196037B2 (en) | 2010-01-18 | 2021-12-07 | Enevate Corporation | Silicon particles for battery electrodes |
US9941509B2 (en) | 2010-01-18 | 2018-04-10 | Enevate Corporation | Silicon particles for battery electrodes |
US11183712B2 (en) | 2010-01-18 | 2021-11-23 | Enevate Corporation | Electrolyte compositions for batteries |
US11380890B2 (en) | 2010-01-18 | 2022-07-05 | Enevate Corporation | Surface modification of silicon particles for electrochemical storage |
US20110177393A1 (en) * | 2010-01-18 | 2011-07-21 | Enevate Corporation | Composite materials for electrochemical storage |
US9178208B2 (en) | 2010-01-18 | 2015-11-03 | Evevate Corporation | Composite materials for electrochemical storage |
US11955623B2 (en) | 2010-01-18 | 2024-04-09 | Enevate Corporation | Silicon particles for battery electrodes |
US10103378B2 (en) | 2010-01-18 | 2018-10-16 | Enevate Corporation | Methods of forming composite material films |
US20140220411A1 (en) * | 2010-02-25 | 2014-08-07 | Lg Chem, Ltd. | Separator for electrochemical device and electrochemical device including the separator |
US9985260B2 (en) * | 2010-02-25 | 2018-05-29 | Lg Chem, Ltd. | Separator for electrochemical device and electrochemical device including the separator |
US20130122353A1 (en) * | 2010-09-02 | 2013-05-16 | Nec Corporation | Secondary battery |
US10038219B2 (en) | 2010-11-15 | 2018-07-31 | Amprius, Inc. | Electrolytes for rechargeable batteries |
US9142864B2 (en) | 2010-11-15 | 2015-09-22 | Amprius, Inc. | Electrolytes for rechargeable batteries |
US11784298B2 (en) | 2010-12-22 | 2023-10-10 | Enevate Corporation | Methods of reducing occurrences of short circuits and/or lithium plating in batteries |
US10431808B2 (en) | 2010-12-22 | 2019-10-01 | Enevate Corporation | Electrodes, electrochemical cells, and methods of forming electrodes and electrochemical cells |
US11837710B2 (en) | 2010-12-22 | 2023-12-05 | Enevate Corporation | Methods of reducing occurrences of short circuits and/or lithium plating in batteries |
US11177467B2 (en) | 2010-12-22 | 2021-11-16 | Enevate Corporation | Electrodes, electrochemical cells, and methods of forming electrodes and electrochemical cells |
US10388943B2 (en) | 2010-12-22 | 2019-08-20 | Enevate Corporation | Methods of reducing occurrences of short circuits and/or lithium plating in batteries |
US10516155B2 (en) | 2010-12-22 | 2019-12-24 | Enevate Corporation | Electrodes, electrochemical cells, and methods of forming electrodes and electrochemical cells |
US10985361B2 (en) | 2010-12-22 | 2021-04-20 | Enevate Corporation | Electrodes configured to reduce occurrences of short circuits and/or lithium plating in batteries |
US9397338B2 (en) | 2010-12-22 | 2016-07-19 | Enevate Corporation | Electrodes, electrochemical cells, and methods of forming electrodes and electrochemical cells |
US9583757B2 (en) | 2010-12-22 | 2017-02-28 | Enevate Corporation | Electrodes, electrochemical cells, and methods of forming electrodes and electrochemical cells |
US9806328B2 (en) | 2010-12-22 | 2017-10-31 | Enevate Corporation | Electrodes, electrochemical cells, and methods of forming electrodes and electrochemical cells |
US9997765B2 (en) | 2010-12-22 | 2018-06-12 | Enevate Corporation | Electrodes, electrochemical cells, and methods of forming electrodes and electrochemical cells |
US9048492B2 (en) | 2011-05-25 | 2015-06-02 | Nissan Motor Co., Ltd. | Negative electrode active material for electric device |
EP3396747A1 (en) * | 2011-06-24 | 2018-10-31 | Nexeon Limited | Structured particles |
US10822713B2 (en) | 2011-06-24 | 2020-11-03 | Nexeon Limited | Structured particles |
WO2012175998A1 (en) * | 2011-06-24 | 2012-12-27 | Nexeon Limited | Structured particles |
GB2502500A (en) * | 2011-06-24 | 2013-11-27 | Nexeon Ltd | Structured Particles |
US10077506B2 (en) | 2011-06-24 | 2018-09-18 | Nexeon Limited | Structured particles |
GB2502500B (en) * | 2011-06-24 | 2018-12-12 | Nexeon Ltd | Pillared Particles |
US9362549B2 (en) | 2011-12-21 | 2016-06-07 | Cpt Ip Holdings, Llc | Lithium-ion battery anode including core-shell heterostructure of silicon coated vertically aligned carbon nanofibers |
US9548489B2 (en) | 2012-01-30 | 2017-01-17 | Nexeon Ltd. | Composition of SI/C electro active material |
US10388948B2 (en) | 2012-01-30 | 2019-08-20 | Nexeon Limited | Composition of SI/C electro active material |
US10103379B2 (en) | 2012-02-28 | 2018-10-16 | Nexeon Limited | Structured silicon particles |
US10090513B2 (en) | 2012-06-01 | 2018-10-02 | Nexeon Limited | Method of forming silicon |
US9368795B2 (en) * | 2012-06-13 | 2016-06-14 | Sango Co., Ltd. | Lithium secondary battery negative electrode and method for manufacturing the same |
US20140170490A1 (en) * | 2012-06-13 | 2014-06-19 | City Of Nagoya | Lithium secondary battery negative electrode and method for manufacturing the same |
US10008716B2 (en) | 2012-11-02 | 2018-06-26 | Nexeon Limited | Device and method of forming a device |
US9093224B2 (en) * | 2012-11-27 | 2015-07-28 | Samsung Electro-Mechanics Co., Ltd. | Electrode structure and method for manufacturing the same, and energy storage device including the electrode structure |
US20140146439A1 (en) * | 2012-11-27 | 2014-05-29 | Samsung Electro-Mechanics Co., Ltd. | Electrode structure and method for manufacturing the same, and energy storage device including the electrode structure |
US20150056510A1 (en) * | 2013-08-20 | 2015-02-26 | Samsung Sdi Co., Ltd. | Negative active material for rechargeable lithium battery, method of preparing same, and negative electrode and rechargeable lithium battery including same |
US9601754B2 (en) * | 2013-08-20 | 2017-03-21 | Samsung Sdi Co., Ltd. | Negative active material for rechargeable lithium battery, method of preparing same, and negative electrode and rechargeable lithium battery including same |
US10396355B2 (en) | 2014-04-09 | 2019-08-27 | Nexeon Ltd. | Negative electrode active material for secondary battery and method for manufacturing same |
US10693134B2 (en) | 2014-04-09 | 2020-06-23 | Nexeon Ltd. | Negative electrode active material for secondary battery and method for manufacturing same |
US10586976B2 (en) | 2014-04-22 | 2020-03-10 | Nexeon Ltd | Negative electrode active material and lithium secondary battery comprising same |
US11289701B2 (en) | 2014-05-12 | 2022-03-29 | Amprius, Inc. | Structurally controlled deposition of silicon onto nanowires |
US9923201B2 (en) | 2014-05-12 | 2018-03-20 | Amprius, Inc. | Structurally controlled deposition of silicon onto nanowires |
US10707484B2 (en) | 2014-05-12 | 2020-07-07 | Amprius, Inc. | Structurally controlled deposition of silicon onto nanowires |
US11855279B2 (en) | 2014-05-12 | 2023-12-26 | Amprius Technologies, Inc. | Structurally controlled deposition of silicon onto nanowires |
US10476072B2 (en) | 2014-12-12 | 2019-11-12 | Nexeon Limited | Electrodes for metal-ion batteries |
US10608257B2 (en) * | 2015-05-08 | 2020-03-31 | Toppan Printing Co., Ltd. | Electrode for nonaqueous electrolyte secondary cell and nonaqueous electrolyte secondary cell |
US20180159135A1 (en) * | 2015-05-08 | 2018-06-07 | Toppan Printing Co., Ltd. | Electrode for nonaqueous electrolyte secondary cell and nonaqueous electrolyte secondary cell |
US10541412B2 (en) | 2015-08-07 | 2020-01-21 | Enevate Corporation | Surface modification of silicon particles for electrochemical storage |
US11309536B2 (en) | 2017-12-07 | 2022-04-19 | Enevate Corporation | Silicon particles for battery electrodes |
US11133498B2 (en) | 2017-12-07 | 2021-09-28 | Enevate Corporation | Binding agents for electrochemically active materials and methods of forming the same |
US10686214B2 (en) | 2017-12-07 | 2020-06-16 | Enevate Corporation | Sandwich electrodes and methods of making the same |
US11916228B2 (en) | 2017-12-07 | 2024-02-27 | Enevate Corporation | Binding agents for electrochemically active materials and methods of forming the same |
US11539041B2 (en) | 2017-12-07 | 2022-12-27 | Enevate Corporation | Silicon particles for battery electrodes |
US11901500B2 (en) | 2017-12-07 | 2024-02-13 | Enevate Corporation | Sandwich electrodes |
US11777077B2 (en) | 2017-12-07 | 2023-10-03 | Enevate Corporation | Silicon particles for battery electrodes |
US10707478B2 (en) | 2017-12-07 | 2020-07-07 | Enevate Corporation | Silicon particles for battery electrodes |
US11891523B2 (en) | 2019-09-30 | 2024-02-06 | Lg Energy Solution, Ltd. | Composite negative electrode active material, method of manufacturing the same, and negative electrode including the same |
US20220302520A1 (en) * | 2021-03-16 | 2022-09-22 | Beam Global | Phase change composite apparatus for battery packs and methods of making |
IT202100017024A1 (en) * | 2021-06-29 | 2022-12-29 | Pierfrancesco Atanasio | Carbon/active material hybrid electrodes for lithium ion batteries |
WO2023275733A1 (en) * | 2021-06-29 | 2023-01-05 | Nanoshare 4.0 Srl | Carbon/active material hybride electrodes for lithium ion batteries |
WO2023044579A1 (en) * | 2021-09-24 | 2023-03-30 | Rangom Yverick Pascal | Electrodes comprising covalently joined carbonaceous and metalloid powders and methods of manufacturing same |
US11387443B1 (en) | 2021-11-22 | 2022-07-12 | Enevate Corporation | Silicon based lithium ion battery and improved cycle life of same |
Also Published As
Publication number | Publication date |
---|---|
WO2007069389A1 (en) | 2007-06-21 |
CN100495769C (en) | 2009-06-03 |
US7892677B2 (en) | 2011-02-22 |
KR100832205B1 (en) | 2008-05-23 |
JP5162825B2 (en) | 2013-03-13 |
KR20070088523A (en) | 2007-08-29 |
JP2007165078A (en) | 2007-06-28 |
CN101061593A (en) | 2007-10-24 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7892677B2 (en) | Negative electrode for non-aqueous electrolyte secondary batteries, and non-aqueous electrolyte secondary battery having the same | |
US20070111102A1 (en) | Negative electrode for non-aqueous electrolyte secondary batteries, non-aqueous electrolyte secondary battery having the electrode, and method for producing negative electrode for non-aqueous electrolyte secondary batteries | |
JP4213687B2 (en) | Nonaqueous electrolyte battery and battery pack | |
JP3726958B2 (en) | battery | |
JP5070753B2 (en) | battery | |
EP2498323A2 (en) | Positive active material, and electrode and lithium battery containing the material | |
EP2618406A1 (en) | Nonaqueous secondary cell | |
EP2192640A1 (en) | Cathode active material, cathode, and nonaqueous electrolyte secondary battery | |
JP2007165079A (en) | Negative electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery using it | |
JP2016062860A (en) | Electrode active material for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery including the same | |
KR20190041420A (en) | Positive electrode active material for lithium secondary battery, preparing method of the same, positive electrode and lithium secondary battery including the same | |
EP1246290A2 (en) | Positive electrode active material and nonaqueous electrolyte secondary battery | |
CN117038880A (en) | Positive active material for lithium secondary battery and lithium secondary battery including the same | |
JP2017520892A (en) | Positive electrode for lithium battery | |
KR20190047195A (en) | Negative electrode active material for lithium secondary battery and lithium secondary battery comprising the same | |
JP2010123331A (en) | Nonaqueous electrolyte secondary battery | |
JP2007220585A (en) | Negative electrode for non-aqueous secondary battery, and non-aqueous secondary battery | |
JP2013131427A (en) | Laminated battery | |
JP2012084426A (en) | Nonaqueous electrolyte secondary battery | |
JP2007188864A (en) | Negative electrode for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery using it | |
JP3530174B2 (en) | Positive electrode active material and lithium ion secondary battery | |
KR20190044444A (en) | Positive electrode active material for lithium secondary battery, preparing method of the same, positive electrode and lithium secondary battery including the same | |
KR20230025318A (en) | Negative electrode active material, negative electrode comprising same, secondary battery comprising same and method for manufacturing negative electrode active material | |
JP2023543242A (en) | Lithium secondary battery manufacturing method and lithium secondary battery manufactured thereby | |
US20240120468A1 (en) | Positive Electrode Active Material For Lithium Secondary Battery, Method Of Preparing The Same, And Lithium Secondary Battery Comprising The Same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD., JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SHIRANE, TAKAYUKI;KASHIWAGI, KATSUMI;INOUE, KAORU;REEL/FRAME:021349/0631 Effective date: 20070313 |
|
AS | Assignment |
Owner name: PANASONIC CORPORATION, JAPAN Free format text: CHANGE OF NAME;ASSIGNOR:MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.;REEL/FRAME:021818/0725 Effective date: 20081001 Owner name: PANASONIC CORPORATION,JAPAN Free format text: CHANGE OF NAME;ASSIGNOR:MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.;REEL/FRAME:021818/0725 Effective date: 20081001 |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
AS | Assignment |
Owner name: GODO KAISHA IP BRIDGE 1, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:PANASONIC CORPORATION (FORMERLY MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.);REEL/FRAME:032152/0514 Effective date: 20140117 |
|
FPAY | Fee payment |
Year of fee payment: 4 |
|
FEPP | Fee payment procedure |
Free format text: MAINTENANCE FEE REMINDER MAILED (ORIGINAL EVENT CODE: REM.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
LAPS | Lapse for failure to pay maintenance fees |
Free format text: PATENT EXPIRED FOR FAILURE TO PAY MAINTENANCE FEES (ORIGINAL EVENT CODE: EXP.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
STCH | Information on status: patent discontinuation |
Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362 |
|
FP | Lapsed due to failure to pay maintenance fee |
Effective date: 20190222 |